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12 October 2026

23 Pages

Forensic DNA Phenotyping in Criminal Investigation: Casework Applications, Deterrence Theory, and the Case for Regulatory Reform

and
1
Faculty of Law, Complutense University of Madrid (UCM), Pl. Menéndez Pelayo, 4, 28040 Madrid, Spain
2
Faculty of Law, Maastricht University, Bouillonstraat 3, 6211 LH Maastricht, The Netherlands
3
Legal Medicine, Psychiatry and Pathology Department, Medicine School, Complutense University of Madrid (UCM), 28040 Madrid, Spain
*
Author to whom correspondence should be addressed.
Forensic Sci.2026, 6(4), 88;https://doi.org/10.3390/forensicsci6040088
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Abstract

Background/Objectives: Forensic DNA phenotyping (FDP), the inference of externally visible characteristics from biological trace evidence, has become an operational investigative tool, yet its implications for criminal justice systems remain poorly understood outside specialist forensic circles. This study examines the scientific foundations, operational utility, and regulatory context of FDP, and situates its findings within a criminological framework that forensic science literature has largely overlooked. Methods: A narrative review of scientific and legal literature was conducted across six electronic databases, covering publications up to 2026. This was complemented by a structured analysis of publicly documented criminal investigations in which FDP was operationally applied, incorporating both successful outcomes and documented failure contexts drawn from peer-reviewed validation studies. Results: Pigmentation traits are predicted with substantial reliability by validated systems; accuracy declines markedly for complex traits and non-European populations. Casework evidence suggests that FDP can contribute to the reactivation of stalled investigations when combined with complementary methods but is insufficient for identification in isolation. Among the nine European jurisdictions examined, several lack explicit legal frameworks governing phenotyping deployment, with Spain serving as a representative example. Conclusions: The disconnect between forensic science and criminal justice practice is itself a governance problem. FDP has shown investigative potential and, in some documented cases, restorative value—particularly in cold cases—but its responsible deployment requires simultaneous progress in scientific validation, regulatory reform, and the professional training of legal practitioners who currently lack the knowledge to deploy or oversee it effectively.

1. Introduction

The history of criminal justice is, in many respects, a history of technological adaptation. From the introduction of fingerprint analysis in the late nineteenth century to the advent of forensic DNA profiling in the 1980s, each successive innovation has redefined the boundaries of what is investigatively possible. Today, a further development is emerging: the ability to infer an unknown individual’s physical appearance directly from biological trace evidence left at a crime scene, without the need for a reference sample or a database match. This capability, known as forensic DNA phenotyping (FDP), represents one of the most significant and most contested developments in contemporary forensic science.
The implications for criminal justice are considerable. In any given year, thousands of criminal investigations worldwide reach an impasse: no suspect has been identified, no genetic match has been found, and the trail has gone cold. For the families of victims, this is an investigative failure. For society, it represents a crack in the deterrent architecture of the criminal justice system. For investigators, it is an unanswered question that may persist for decades. Forensic DNA phenotyping offers the possibility of generating an investigative lead from biological evidence alone, a portrait of an unknown individual reconstructed from the molecular information encoded in their DNA.
From a criminological standpoint, this development can be examined through two complementary theoretical lenses. The first is deterrence theory [1,2], within which the certainty of punishment is widely recognised as the most powerful deterrent to criminal behaviour—considerably more so than its severity [3]. Cold cases represent a structural failure of this certainty: when investigations stall and perpetrators remain unidentified, the deterrent function of the criminal justice system is fundamentally undermined. The longer a case remains unsolved, the more clearly it signals, to potential offenders and to society alike, that certain crimes may be committed without consequence. Forensic DNA phenotyping addresses this gap by extending the investigative reach of law enforcement beyond the limitations of conventional genetic databases, thereby increasing the probability of offender identification and, with it, the perceived certainty of apprehension.
The second lens is restorative justice theory [4,5], which draws attention to the needs of victims and their families as central, and frequently overlooked, actors in the criminal justice process. Cold cases impose a prolonged burden of unresolved grief upon victims’ families, denying them the closure, recognition, and accountability that justice proceedings might otherwise provide. The capacity of FDP to reactivate stalled investigations carries, therefore, a restorative dimension that extends well beyond the strictly punitive objectives of criminal law.
These two theoretical perspectives together provide the criminological framework within which the present study situates its analysis. Rather than evaluating FDP solely on technical or legal grounds, this study examines its broader implications for criminal justice systems, its potential to extend investigative reach in cases where conventional methods have failed, and to address the legitimate interests of victims and their families, whilst also confronting the ethical and legal tensions that this technology inevitably generates: between the imperatives of justice and the demands of privacy, between scientific possibility and legal permissibility, between the promise of identification and the risk of discrimination.
This study is structured around two complementary analytical dimensions. The first draws on operational evidence from the United States, the jurisdiction in which FDP has been most extensively deployed and documented, to assess the technology’s investigative utility and its capacity to contribute to the resolution of criminal cases that had remained open for decades. The United States is examined as an operational reference case because its regulatory framework for forensic DNA phenotyping is less strict than those emerging in several European jurisdictions, a context that has allowed its deployment and documentation at a scale not yet observed in Europe, providing an empirical evidence base from which European regulatory debates can usefully draw. The second dimension examines the regulatory frameworks governing FDP across nine European jurisdictions, with particular attention to the Spanish context as an example of the legislative gaps that characterise several of the European jurisdictions examined in this study. The juxtaposition of these two dimensions is deliberate: the American casework evidence establishes what the technology can do; the European regulatory analysis establishes what legal and institutional conditions are required for it to be deployed responsibly.
One obstacle to the responsible use of forensic DNA phenotyping receives less attention than it deserves: the gap between those who develop the technology and those who use it. Forensic geneticists publish advances in prediction methods without systematic engagement with how investigations work; law enforcement officers and legal practitioners, in turn, make decisions about a technology they rarely have the training to evaluate. This study is written with both groups in mind, not to water down the science, but because the distance between the laboratory and the courtroom is itself part of the problem.
In this sense, the specific objectives of this study are to evaluate the scientific foundations and current capabilities of FDP; to assess its operational utility through the analysis of resolved criminal casework; to examine the ethical and legal limitations of this methodology; and to analyse the regulatory frameworks governing its use across selected European jurisdictions.

2. Scientific Foundations of Phenotype Genetics

The human genome comprises the complete set of genetic material organised into 23 pairs of chromosomes, of which approximately 20,000 protein-coding genes—representing only 2% of the total DNA content—are responsible for protein synthesis and the expression of observable physical traits [6,7,8,9]. The remaining 98% consists of non-coding DNA, which serves regulatory and structural functions and has traditionally been the focus of forensic genetics, enabling the construction of genetic profiles for comparison and identification purposes [10,11]. These profiles, however, are useful only when a reference sample is available for direct comparison, they provide no information about the physical appearance of an unknown individual.
This limitation has driven the development of forensic DNA phenotyping, which analyses single-nucleotide polymorphisms (SNPs) (specific positions in the genome where individuals differ by a single DNA base) to infer externally visible characteristics (EVCs) directly from biological trace evidence. The human phenotype, defined as the set of observable physical characteristics resulting from the interplay between an individual’s genetic makeup and environmental factors, thus becomes, at least partially, accessible without the need for a reference sample [12,13,14].

2.1. Externally Visible Characteristics and Associated Genetic Markers

The forensic relevance of DNA phenotyping depends on the identification of genetic markers reliably associated with specific EVCs. Research to date has focused on two broad categories. The evidence supporting the FDP varies considerably depending on its stage of development. Four distinct levels can be identified: genetic association studies that identify variants linked to a trait; the development of predictive models, in which these variants are combined into a statistical classifier; analytical validation, in which the model’s performance is tested under controlled laboratory conditions; and operational forensic validation, in which performance is assessed on the types of samples encountered in practice—often degraded, in limited quantities or of mixed origin. The characteristics listed below are supported primarily by evidence from genetic association studies and model development; analytical and operational forensic validation exists for some of them, but not for all, and this distinction is maintained throughout the manuscript.

2.1.1. Facial Features and Craniofacial Structure

The shape of the face and skull is one of the most complex human traits, influenced by hundreds of genetic variants. Its study is fundamental to anthropology, medicine, and forensic genetics. Characteristics for which genetic association evidence exists include: Nose Morphology [15,16]; Chin and Jaw Shape [17]; Interpupillary Distance [18]; Ear Shape [17,18]; Eye Shape [19]; Eyelashes [17,20]; Beard [17]; Hairline [15,17]; Eye Colour [21]; Hair Colour [22]; Red Hair [23].

2.1.2. Morphological and Body Characteristics

Forensic genetics is expanding beyond facial features to include other physical characteristics that contribute to a more complete profile of an unknown individual. Characteristics for which genetic association evidence exists but forensic predictive validation remains limited include Height [24,25,26]; Baldness [27,28]; Body Mass Index and Fat Distribution [29,30,31]. These traits are influenced by a large number of genetic variants and by environmental factors, and current models do not yet achieve the predictive accuracy required for operational forensic use.
The majority of these traits are polygenic, meaning that their expression results from thousands of genetic variants acting in concert, many of which remain incompletely characterised. Predicting a specific trait from DNA is therefore less about producing an exact representation than about estimating a probability of appearance. The most reliably predicted traits at present are eye, hair, and skin colour. Research into most other characteristics is ongoing, and their forensic application remains subject to important limitations that are addressed in the sections that follow.

3. Methodology

This study is a narrative review structured around two complementary analytical dimensions: a review of the scientific and legal literature on Forensic DNA phenotyping, and an analysis of publicly documented criminal investigations in which phenotyping was operationally applied. This design reflects the broad and interdisciplinary nature of the research objectives, which span scientific, legal, ethical, and criminological dimensions of a field that remains heterogeneous and rapidly evolving. The aim is not to produce an exhaustive or systematic review of the literature, but rather to map the existing evidence base, identify the main gaps in research and situate the scientific evidence within a criminological framework that has received limited attention in the existing literature. Source selection was therefore purposive rather than exhaustive, guided by relevance and analytical contribution.

3.1. Literature Search and Selection

A search was conducted across six electronic databases—Dialnet, Scopus, ScienceDirect/Elsevier, PubMed, SciELO, and Google Scholar, covering publications up to September 2025. This structured search was complemented by a targeted supplementary search conducted between January and August 2026 to identify recent validation studies published after the initial search date, with particular attention to population-specific performance data and emerging casework literature. The following search terms were used individually and in combination: phenotypic prediction from DNA, SNPs and physical traits, externally visible characteristics (EVC), HIrisPlex, forensic DNA phenotyping, and VISAGE Project.
The search identified a substantial body of literature, from which sources were selected based on direct relevance to the research objectives, methodological quality, and contribution to the analytical dimensions of the review. A total of 86 sources is cited in the present manuscript. Inclusion criteria were studies published from 2015 onwards, with the supplementary search extending coverage through to August 2026 to incorporate emerging validation literature, except for seminal earlier references essential to contextualise the field; publications with direct applicability to forensic science or criminal investigation; and legal, doctrinal, or regulatory documents of current or historical relevance. Exclusion criteria comprised: articles unavailable in full text; studies focused exclusively on the prediction of medical conditions unrelated to forensic identification; and sources lacking sufficient methodological rigour.
The included literature serves two distinct functions. Approximately 70% of the cited works constitute the primary analytical corpus (empirical studies, validation research, and legal analyses directly concerned with FDP). The remaining 30% provide contextual background in forensic genetics, molecular biology, and criminal procedure, cited in the introductory and scientific foundations sections to situate the topic within its broader disciplinary context.

3.2. Selection and Analysis of Forensic Casework

In parallel, a structured review of publicly documented criminal investigations in which forensic DNA phenotyping had been operationally applied was conducted. Case documentation was drawn from two types of source: academically cited case reports, in which the role of FDP in the investigation is described in peer-reviewed literature; and publicly disclosed case records from Parabon NanoLabs®, Inc. (Reston, VA, USA), the only commercial provider currently known to maintain a publicly accessible repository of resolved investigations with sufficient detail, including predicted phenotypic profiles, investigative methods, and identification outcomes to enable academic analysis. Where Parabon NanoLabs® case data were used, authorisation was obtained before inclusion in this study. The company neither supplied, selected, nor reviewed any material within this manuscript; all cases analysed were drawn exclusively from publicly available documentation.
Cases were included based on two criteria: the individual sought, whether suspect or victim, had been definitively identified; and forensic DNA phenotyping had played a documented role in the investigative process. No restriction was placed on the direction of that role: cases in which FDP contributed to a successful outcome and cases in which it produced inconclusive or limited results were both considered for inclusion, to the extent that such documentation is available in the published literature.
The operational literature on FDP does not currently provide systematic documentation of cases in which the technology failed or produced misleading predictions. This absence of negative outcomes from the public record is a recognised limitation of the field, addressed in detail in Section 6.5. The casework analysis presented in this study should therefore be read as illustrative of the conditions under which FDP has shown investigative utility in specific documented contexts, rather than as a representative sample of its overall performance.

4. Practical Applications in Forensic Genetics

Forensic DNA phenotyping (FDP) encompasses a range of distinct yet complementary applications, which differ in their technical basis and forensic utility. The prediction of external visible characteristics (EVCs) (eye, hair and skin colour, facial morphology) is based on the genotyping of specific genomic coding regions using SNPs. The inference of biogeographical ancestry uses ancestry-informative markers (AIMs) to determine the population origin of an unknown individual. Epigenetic age estimation, the identification of bodily fluids and the inference of lifestyle characteristics, such as smoking, are based on DNA methylation patterns rather than sequence variants and represent a separate analytical domain. Investigative genetic genealogy, on the other hand, involves searching consumer DNA databases by relatives of an unknown individual and is a distinct methodology that may complement, but is not part of, the FDP. Each of these applications is discussed in the following sections [32,33,34,35,36].

4.1. Predictive Methodology

The predictive capacity of FDP rests on the identification of single-nucleotide polymorphisms (SNPs) positions in the genome where individuals differ by a single-nucleotide polymorphisms (SNPs), positions in the genome where individuals differ by a single DNA base. These variants may be located in coding, intronic, inter-genic or regulatory regions; their forensic relevance depends on their association with phenotypic traits rather than on their genomic location. These markers are selected for their genetic stability, low mutation rate, and capacity to be analysed in degraded or low-quantity samples, which makes them particularly suitable for forensic casework [36,37,38,39].
The identification of relevant SNPs has been driven largely by genome-wide association studies (GWAS), which compare genetic variants across large populations to identify those associated with particular traits. The development of next-generation sequencing (NGS) has accelerated this process considerably, enabling the simultaneous analysis of large numbers of markers and the application of increasingly sophisticated statistical models [39,40,41,42].
Once informative SNP panels have been identified, statistical models (typically multinomial logistic regression) are used to weigh the contribution of each marker and generate probability estimates for different phenotypic outcomes [43]. The result is not a definitive description but a probabilistic profile: the prediction may indicate, for example, that there is an 87% probability of blue eyes, or a 72% probability of light skin.
A critical consideration in panel design is population context. The same SNP may be highly informative in one population and uninformative in another. The variant rs1426654, located in the SLC24A5 gene, illustrates this well: it accounts for a significant proportion of skin colour variation in South Asian populations but is largely fixed in European and East Asian populations, where it therefore adds no predictive value [43,44,45]. This population dependency highlights the importance of establishing biogeographical ancestry before generating phenotypic predictions and highlights a broader equity concern: most validated prediction systems were developed primarily using European cohorts, and their performance in admixed or non-European populations is systematically lower [46,47].
The most widely validated forensic phenotyping system is HIrisPlex-S, which simultaneously predicts eye, hair, and skin colour from 41 SNPs using a targeted genotyping approach. In a validation study using skeletal remains of Italian provenance, HIrisPlex-S achieved overall prediction accuracy exceeding 90% for these three traits at a probability threshold of 0.7, with the most reliable predictions obtained for individuals with extreme pigmentation—dark brown eyes, black or red hair, very pale or very dark skin [33]. Performance is lower for intermediate pigmentation categories, which remain the principal source of inconclusive results [22,33,48,49,50]. Intermediate colours, particularly intermediate eye and hair colour, remain the principal source of inconclusive results and represent the main focus of ongoing refinement research [33,48].
Commercial systems also exist, most notably the Snapshot Forensic DNA Phenotyping System developed by Parabon NanoLabs®, Inc. (Reston, VA, USA), which uses machine learning algorithms to predict pigmentation, facial morphology, the presence of freckles, and other traits. Unlike HIrisPlex-S, Parabon NanoLabs®, Inc. (Reston, VA, USA) has not published the technical details of its algorithm or independent validation studies in peer-reviewed journals, which limits external evaluation of its reliability [44].

4.2. Current Capabilities and Documented Limitations

The forensic utility of FDP varies considerably depending on the trait being predicted, the quality of the biological sample, and the population background of the individual concerned. This section reviews what the current evidence base supports, and where its limits lie.

4.2.1. Traits with Established Predictive Reliability

Eye, hair, and skin colour are the traits for which the most robust forensic validation exists, as can be consulted in Table 1. Performance varies by population, sample type, and pigmentation category, as documented in Table 2.
Table 1. Selected documented cases illustrating the investigative role of forensic DNA phenotyping, including cases of limited utility.
Table 2. Documented performance limitations of forensic DNA phenotyping systems in validation studies and operational contexts.
Biogeographical ancestry can be estimated using ancestry-informative markers (AIMs), genetic variants that differ substantially in frequency across population groups. Validated panels such as ThermoFisher’s Precision ID Ancestry Panel include 165 such markers, enabling differentiation of major global population groups and providing contextual information that can guide phenotypic prediction [44,55].
Biological age estimation through DNA methylation analysis represents a more recent but increasingly validated area of FDP. Machine learning models based on selected CpG methylation sites have demonstrated a mean absolute error of approximately 3.8 years in validation studies, and NGS platforms are being developed that can quantify methylation status alongside pigmentation and ancestry predictions [56,57].
DNA methylation is an epigenetic mechanism in which methyl groups are added to specific positions in the genome—predominantly at CpG sites—altering gene expression without changing the underlying DNA sequence. Unlike the genetic variants used in SNP-based phenotyping, methylation patterns are dynamic: they vary across tissues, change with age, and respond to environmental exposures such as diet, smoking, and disease. This makes the epigenome informative in ways that genotype alone cannot be, and it is this property that gives methylation-based analysis its forensic value [57,58].
Beyond age estimation, DNA methylation extends forensic phenotyping into areas that SNP-based methods cannot reach. Tissue and body fluid identification, distinguishing blood, saliva, semen, vaginal fluid, menstrual blood, urine, skin, and sweat from a single biological sample, is now one of the most established forensic applications of methylation analysis, with practical implications for reconstructing the circumstances of an offence [58,59]. Methylation patterns have additionally been used to infer lifestyle characteristics such as smoking status, where specific CpG sites show consistent epigenetic changes associated with tobacco exposure [57,58]. More limited evidence exists for methylation-based prediction of pigmentation traits—eye, hair, and skin colour—which remain better served by validated SNP panels; in this area, methylation is better understood as a promising extension than as an established forensic tool [60,61].
The practical constraints of methylation-based phenotyping should be noted alongside its potential. Current methods generally require higher-quality DNA than SNP genotyping, standardised workflows remain lacking, and methylation patterns can be influenced by disease states or environmental factors in ways that introduce interpretive uncertainty [62,63]. These limitations do not diminish its forensic value, but they define the conditions under which it can be reliably deployed.

4.2.2. Complex Traits and Documented Limitations

Facial morphology, height, and body composition remain substantially less tractable than pigmentation traits. These characteristics are highly polygenic, influenced by large numbers of genetic variants, many of which remain incompletely characterised, and are additionally shaped by environmental factors in ways that pigmentation traits are not. Research in this area has grown considerably, with GWAS and whole-exome sequencing studies identifying candidate variants associated with specific facial features [18,64], but the predictive models derived from this research are not yet sufficiently reliable for operational forensic use.
Beyond trait complexity, the literature documents several recurring contexts in which FDP performs poorly or produces misleading results. In a study of 20 sets of skeletal remains, two cases yielded inconclusive predictions, both involving individuals with intermediate pigmentation [33]. In a Norwegian population cohort, intermediate eye colour was not predicted in any individual, producing error rates of 37% without probability thresholding [48]. In a North German cohort, intermediate eye colour achieved 0% sensitivity using the HIrisPlex-S system, and hair and skin colour predictions provided only broad directional information rather than fine discrimination [49]. In admixed Latin American populations, accuracy has been shown to decline substantially: in one Mexican cohort, overall eye-colour prediction accuracy fell to 56.1% under partial genotyping conditions [53].
These findings are not incidental. They reflect a structural limitation of current FDP systems: the cohorts used to develop predictive models have been drawn disproportionately from populations of European ancestry, with the result that predictive performance is systematically lower, and the risk of misleading investigative leads correspondingly higher for individuals from underrepresented population groups [46].

4.3. Documented Casework Applications

The operational deployment of FDP in criminal investigations has been documented primarily in the United States, where its use has been most extensively recorded. The available evidence suggests that FDP functions most effectively not as a stand-alone identification tool but as a means of generating investigative leads that are subsequently confirmed through conventional DNA profiling or other forensic methods [34,35].
Table 1 summarises documented cases in which FDP contributed to the resolution of criminal investigations, drawing on academically cited sources. Table 2 summarises the principal context in which FDP has been shown to produce inconclusive or unreliable results, based on validation studies.
The cases in Table 1 illustrate the typical operational pattern: FDP generates a probabilistic appearance profile from crime-scene DNA, which narrows the investigative field and, when combined with genetic genealogy or conventional profiling, enables identification. In none of the documented cases was forensic DNA phenotyping sufficient for identification on its own; across every instance, definitive identification required STR confirmation, investigative genetic genealogy, dental records, or another independent methodology. Rather than a limitation to be overcome, this constitutes a structural feature of the technology that must be preserved by design. Forensic DNA phenotyping generates probabilistic predictions of physical appearance and biogeographical ancestry; it does not produce a unique biometric identifier. Relying upon it as a direct basis for identification without independent corroboration would be scientifically indefensible and legally unjustifiable, much like grounding a criminal conviction solely on an eyewitness description. Its proper functional role remains upstream of identification: it narrows the investigative scope and generates hypotheses that must subsequently be rigorously tested through confirmatory methods. Any regulatory or operational framework permitting forensic DNA phenotyping results to stand as standalone identification evidence would fundamentally misinterpret the technology’s capabilities, exposing individuals to the severe risk of misidentification driven by probabilistic trait predictions. FDP’s contribution was to narrow the investigative field and generate leads that made those confirmatory steps possible. The limitations documented in Table 2 are equally instructive: they define the boundaries within which FDP can be reliably deployed and highlight the populations and sample conditions for which current systems are not yet fit for purpose.

5. Criminological Implications: Deterrence, Restorative Justice, and the Case for Regulatory Reform

The preceding sections have established what forensic DNA phenotyping can do technically and what it has achieved operationally. This section addresses a question that the forensic science literature has largely left unanswered: what does this technology mean for criminal justice systems as a whole, for the people who commit crimes, for the victims and families who bear their consequences, and for the legal frameworks that are supposed to govern both?
This is where the present study makes its most distinctive contribution. Existing reviews of FDP are written almost exclusively from a scientific or legal standpoint. None has examined the technology through the lens of criminological theory, and none has situated its operational evidence within the frameworks—deterrence theory and restorative justice—that are central to understanding how criminal justice systems function and fail. This section does both.

5.1. Deterrence Theory and the Problem of Unresolved Investigations

Deterrence theory, developed from the foundational work of Beccaria (1995) and Becker (1968) and extensively tested in subsequent criminological research [1,2], holds that criminal behaviour is discouraged primarily by the perceived certainty of punishment, more so than by its severity. When the probability of being caught and prosecuted is low, the deterrent function of the criminal justice system is structurally weakened, regardless of the penalties formally in place.
Cold cases represent precisely this kind of structural failure. A crime that remains unsolved for decades sends a clear signal, to potential offenders and to society alike, that certain acts can be committed without consequences. The deterrent architecture of the criminal justice system depends on closure; without it, impunity becomes, in effect, institutionalised.
Forensic DNA phenotyping addresses this gap directly. By generating investigative leads from biological evidence that cannot be matched to any existing database profile, it extends the reach of law enforcement into cases that would otherwise remain permanently open. The operational evidence reviewed in this study, cases resolved after gaps of ten, twenty, and in some instances nearly forty years, illustrates this capacity concretely. Interpreted in this theoretical perspective, the contribution of FDP to deterrence lies in its documented capacity increase the likelihood of identification in cases where conventional methods have been exhausted—thereby reducing, at least potentially, the structural impunity represented by long-standing, unsolved investigations.
This argument, however, carries important qualifications. The empirical literature on deterrence demonstrates that certainty of punishment exerts a stronger deterrent effect than severity, operating primarily through the perceived risk of detection rather than awareness of specific investigative techniques [3]. Forensic DNA phenotyping does not alter punishment severity; instead, it potentially increases the probability of detection in complex, previously intractable cases lacking conventional database matches or eyewitness testimony. The criminological rationale for forensic DNA phenotyping is therefore not general deterrence, but the mitigation of a structural gap in detection capacity that otherwise constitutes de facto impunity for a specific subset of serious offences. The deterrent effect of any investigative tool depends on public awareness of its existence and capabilities. FDP is not yet widely known beyond law enforcement circles. Moreover, deterrence theory itself has been subject to significant empirical and theoretical scrutiny, and its predictions do not apply uniformly across offence types, offender populations, or social contexts [3]. The claim advanced here is therefore a measured one: that FDP has the potential to contribute to deterrence by reducing the structural impunity that long-standing unresolved crimes represent, not that it will eliminate offending.

5.2. Restorative Justice and the Needs of Victims’ Families

Restorative justice theory [4,5] draws attention to the needs of victims and their families as central actors in the criminal justice process. Where the punitive model of justice focuses on offenders and their punishment, restorative justice emphasises the harm caused to victims and the importance of acknowledgement, accountability, and, where possible, closure.
Cold cases impose a particular and prolonged burden on victims’ families. When an investigation stalls and no perpetrator is identified, families are denied the legal proceedings, the public accountability, and the formal recognition of harm that a concluded case would provide. The unresolved status of the crime can persist for decades, structurally excluding victims’ families from any form of justice.
The public statement made by Carl Alston—the father of Candra Alston, who was murdered in 2011—at the time the FDP reopened an investigation that had been stalled for four years, illustrates the human context on which this theoretical argument is based: “I implore the public to help find the person who murdered my daughter and my granddaughter. It is difficult for me to come to terms with what happened, and I still find it hard to believe that my daughter and my granddaughter are gone” (Parabon NanoLabs®, Inc. (Reston, VA, USA), 2015). This is not presented as evidence that the FDP has produced a restorative justice outcome—formal restorative processes involve recognition, accountability and, often, direct engagement between the parties, none of which is guaranteed by identification alone. It is presented as evidence of the unmet restorative need created by unresolved investigations and of the FDP’s potential to restore the possibility of a justice process where this had been structurally rendered unfeasible. This is not an isolated instance. Across the cases reviewed in this study, the pattern is consistent: investigations that had been cold for years or decades were reactivated through the application of FDP, ultimately resulting in identifications that enabled formal legal proceedings to take place. For the families of victims, the significance of this outcome extends beyond the punitive, it represents the restoration of a process from which they had been excluded by the failure of conventional methods.
This connection between the FDP and the reparation needs of the families of the victims has begun to receive explicit attention in specialized literature. Benítez Boldo (2026) analyses the psychological and criminological implications of the FDP, defining its role in the reconstruction of identity as a source of institutional confidence and symbolic security for families, a dimension that deserves explicit recognition in political debates about the ends that are expected to fulfil the FDP [65]. It does not depend on overstating the technology’s capabilities or ignoring its limitations. It rests on the more modest but defensible claim that, in cases where all other methods have failed, FDP has in some instances made justice possible where it would otherwise have been impossible.

5.3. The Regulatory Gap and Its Consequences

The criminological case for FDP, both its deterrent potential and its restorative value, cannot be separated from the legal frameworks that govern its use. Technology without governance is not a neutral condition: it is one in which the benefits may be realised unevenly, the risks fall disproportionately on the most exposed populations, and accountability is structurally absent.
Nine jurisdictions were selected using three criteria: documented legislative action or judicial precedent specifically addressing forensic DNA analysis beyond STR profiling; geographic and legal diversity spanning European legal traditions; and the availability of primary legislative sources within academic literature. The United Kingdom is included as a non-EU jurisdiction because of its historical and continued significance in European forensic governance debates. This sample is non-exhaustive and does not support generalisation to all EU member states; consequently, claims in this manuscript regarding the regulatory landscape across Europe are strictly limited to the jurisdictions analysed. The comparative analysis presented in this study reveals that several of the jurisdictions examined have not yet enacted explicit legal framework governing the use of FDP. Table 3 summarises the current regulatory frameworks across nine European countries.
Table 3. Comparative overview of the legal frameworks governing forensic DNA phenotyping in selected European jurisdictions.
The jurisdictions that have enacted targeted frameworks—Germany [66], The Netherlands [67], Slovakia [68], and Switzerland [69]—share a common architecture: explicit statutory authorisation, a defined scope limited to specific traits, a requirement for judicial or equivalent independent oversight, and the principle of subsidiarity, under which FDP may be deployed only when conventional methods have been exhausted. These features are not merely formal safeguards; they constitute the conditions under which the technology can be deployed in a manner that is both effective and rights-respecting.
Spain exemplifies the regulatory gap that characterises several of the European jurisdictions examined in this study. Organic Law 10/2007 restricts forensic DNA analysis to non-coding markers for identification purposes, without explicitly addressing phenotypic prediction. The Eva Blanco case (1997, resolved 2014) demonstrated that ancestry inference is possible within this framework under judicial authorisation, but it also demonstrated its limits: the case required the judiciary to fill a gap that the legislature had not addressed [44]. The Spanish Ministry of Justice’s 2019 guidelines [70] acknowledged this gap and recommended that phenotyping be restricted to cases without database matches, that judicial authorisation be required in all instances, and that legal professionals receive specialised training before deployment These recommendations have not yet been translated into legislation. In the Spanish context, three legally distinct questions must be separated: performing phenotypic analysis on a biological sample; using the resulting data as an investigative lead; and storing those results in a police DNA database. Organic Law 10/2007 governs exclusively the third aspect—the conditions for including profiles in the national forensic DNA database. Although the Eva Blanco precedent addressed the first two questions via judicial authorisation, the absence of explicit legislation means each application requires individual judicial oversight, lacking a standardised framework for admissibility or scope.
Apart from the question of which characteristics to permit and under what conditions, responsible governance of the FDP requires attention to be paid to various operational and structural risks. The communication of probabilistic predictions is a well-documented problem. FDP results are reported in formats that vary widely between providers, and the statistical framework used for the conventional identification of STRs does not apply directly to phenotypic prediction [39]. Police officers are more willing than forensic scientists or lawyers to accept lower reliability standards in exchange for perceived utility [73], and 63 per cent of police officers surveyed in one study were unfamiliar with what current systems can offer [74]. This gap between how predictions are generated and how they are understood creates conditions for a narrow perspective in investigations: a phenotypic profile received at the start of an investigation can restrict the focus of the investigation in ways that are difficult to reverse. A systematic review of 29 studies found confirmation bias among forensic professionals in 9 of the 11 studies that examined the issue, with police investigators exhibiting a stronger narrow view than laypeople, even when there was contradictory evidence [75,76]. Three structural risks have received consistent attention in the literature. Firstly, group privacy: since FDP inferences are based on population-level data, a prediction about an individual implicitly produces suspect groups defined by shared ancestry and appearance, with well-documented risks of racial stigmatisation of communities [77,78,79], This dynamic has been described as the “collectivization of suspicion” [80]: by grouping population groups that share genetic ancestry and externally visible characteristics, the FDP risks increasing the investigative visibility of specific communities beyond the individual being investigated. Forensic geneticists themselves have pointed out this tension, distancing their scientific work from its implications in the criminal justice system, while leaving it to researchers to manage the epistemic risks of probabilistic predictions [81]. Secondly, the retention and secondary use of data: biological samples retain genetic information beyond that for which they were collected, and current European regulations offer inadequate protection against the undue expansion of functions—the gradual extension of a technique beyond its original purpose [79,82,83]. Thirdly, accountability for misleading results: there is no established mechanism for review or redress when a phenotypic prediction proves inaccurate and contributes to a misdirection of research. The literature describes a structural gap whereby the consequences of misinterpretation fall on researchers, rather than on those who generated the forecast [81,84]. These risks do not preclude the use of FDP, but they do justify the creation of governance structures that go beyond the authorisation of specific features. Finally, it is also vitally important that laboratories working in forensic genetics, as well as in forensic genetic genealogy, are fully accredited, for example, by an international standard such as ISO 17025 (2017) [85], since this allows for the elimination, as far as possible, of methodological doubt in obtaining forensic results.
The consequence of this regulatory inertia is not that FDP goes unused—in several jurisdictions, it is deployed under judicial precedent or investigative discretion in the absence of a formal framework. The consequence is that its use is ungoverned: there is no systematic oversight, no standardised criteria for deployment, no mechanism for accountability when predictions prove inaccurate or misleading, and no protection for the individuals—disproportionately from non-European population groups, as the evidence reviewed in Section 4 demonstrates—who are most likely to bear the costs of unreliable predictions.
Legislative reform is therefore not merely a matter of legal tidiness. It is a precondition for the responsible and equitable deployment of a technology whose investigative and restorative potential is supported by the available evidence, but whose risks, if unaddressed, will fall unevenly and without recourse. A further regulatory development warrants attention. Regulation (EU) 2024/982 (the revision of the Prüm II framework on the automated exchange of data for police cooperation) does not explicitly address coding DNA data, but its removal of references to non-coding DNA and the extension of the framework for the exchange of genetic data may indirectly facilitate the future consideration of FDPs in transnational police cooperation. This development reinforces the urgency of proactive legislative frameworks that define the conditions for the use of FDPs before operational practice outstrips regulatory capacity [65,86]. The principle of strict necessity, established in EU data protection law and reflected in the Council of Europe Convention 108+, dictates that any processing of genetic data for law enforcement purposes must be restricted to what is strictly necessary for a given investigative objective. This principle applies directly to forensic DNA phenotyping deployment and must underpin any national legislative framework.

6. Discussion

The evidence reviewed in this study supports a central argument: forensic DNA phenotyping has moved beyond proof of concept and into operational use, with documented capacity to reactivate criminal investigations that had resisted all conventional methods. At the same time, the evidence base reveals persistent scientific constraints, an irregular regulatory scene across European jurisdictions, and ethical tensions that remain unresolved. This discussion addresses four interconnected dimensions: the investigative utility of FDP as evidenced by the casework reviewed; its scientific capabilities and current limits; its broader criminological significance; and the legal challenges it poses, with reference to the Spanish context.

6.1. Investigative Utility

The casework evidence reviewed in this study, drawing on academically cited sources alongside documented cases from Parabon NanoLabs®, Inc. (Reston, VA, USA), illustrates a consistent operational pattern: FDP generates a probabilistic appearance profile from biological trace evidence, which narrows the investigative field and, when combined with genetic genealogy or conventional DNA profiling, enables identification in cases where no database match exists. In none of the documented cases was FDP sufficient for identification on its own; definitive identification required, in every instance, an independent confirmatory method—whether a direct DNA match, a confirmed genealogical link, or dental records. This finding is consistent with the scientific understanding of phenotypic profiles as investigative tools, not identificatory evidence.
Prediction fails most consistently in three contexts: individuals with intermediate pigmentation, non-European or admixed populations, and cases where sample quality is insufficient for complete genotyping. These failure modes are not incidental; they define the boundaries of responsible operational deployment and highlight the populations for whom current systems are least fit for purpose.
The broader operational record of Parabon NanoLabs®, Inc. (Reston, VA, USA), which documented positive identifications in over 200 cases processed between 2019 and 2021, lends weight to the conclusion that FDP, used as part of a multi-method investigative strategy, constitutes a genuinely useful tool. However, this record shares the same structural limitation as the cases reviewed in this study: it reflects only successful outcomes. The absence of systematic documentation of cases in which FDP produced inconclusive or misleading results is a significant gap in the evidence base, and one that must be addressed before any robust assessment of overall efficacy is possible. The only published case in which genetic data analysis (FDP) was applied in a real investigation and documented as having made even a minimal contribution is Operation Minstead [52]—the investigation into the serial sex offender Delroy Grant by the UK Metropolitan Police. In this case, the inference of ancestry and pigmentation based on SNPs did not contribute significantly to the progress of the investigation, a shortcoming attributed to mixed ancestry, the opacity of the commercial panels used, and insufficient genetic coverage for individuals of predominantly African ancestry [52]. This case is instructive precisely because it illustrates the conditions under which current PID systems are least reliable—mixed-race populations, opaque commercial tools, and traits for which the underlying genetic architecture in non-European groups remains poorly characterised.

6.2. Scientific Capabilities and Current Constraints

The predictive reliability of FDP varies considerably across trait categories. Pigmentation traits—eye, hair, and skin colour—are the traits for which the most robust forensic validation currently exists. In validation studies using skeletal remains, HIrisPlex-S has achieved an important accuracy for extreme pigmentation categories; accuracy declines substantially for intermediate pigmentation and for non-European populations [33]. Biological age estimation through DNA methylation analysis is also increasingly well validated, with machine learning models demonstrating mean absolute errors of approximately 3.8 years [56,57].
Beyond these traits, predictive reliability declines substantially. Facial morphology remains the most forensically valuable and least tractable target: research has identified large numbers of genetic variants associated with facial features, yet the data requirements for reliable prediction, particularly for non-European populations, have not yet been met [18,64]. Height, body mass index, and androgenic alopecia are similarly constrained by the pronounced environmental modulation of these traits.
The population representation problem cuts across all trait categories. Most GWAS cohorts and validation studies have been conducted predominantly in populations of European ancestry, with the result that predictive accuracy is systematically lower for individuals of non-European or admixed backgrounds [46,47]. This is not a peripheral concern: it means that FDP is least reliable precisely for those population groups already disproportionately represented in contact with the criminal justice system. Diversifying GWAS reference cohorts is therefore both a scientific priority and an ethical imperative [87].
The Snapshot system from Parabon NanoLabs®, Inc. (Reston, VA, USA) presents a further constraint that distinguishes it from academically validated systems: the absence of published technical details and independent peer-reviewed validation. This opacity limits external scientific review and prevents independent verification of the accuracy of its predictions. Transparent, independently validated systems are a prerequisite for the legally defensible integration of FDP into criminal justice practice. This lack of transparency was noted not only by legal experts, but also by forensic geneticists themselves. Granja and Machado (2023) [81], in interviews with forensic genetics professionals in thirteen European countries, found that Parabon’s Snapshot system was viewed critically by the scientific community. It is characterised as operating within a “political economy of hope” that commercialises predictions without subjecting them to peer review, creating a “semi-transparent box” in which epistemic risks remain visible, but responsibility for managing them is transferred to the police authorities.

6.3. Criminological Implications

The criminological significance of FDP extends beyond investigative efficiency. Examined through the two theoretical frameworks introduced in this study, the operational evidence acquires a broader meaning.
Interpreted through this theoretical lens, FDP’s contribution lies in its documented capacity to extend the investigative reach of law enforcement into cases where conventional methods have failed—potentially reducing the structural impunity that long-standing unresolved crimes represent.
The criminological implications of this evidence are addressed in full in Section 5. The cases reviewed are consistent with the theoretical arguments developed there, but do not constitute independent empirical evidence of deterrent or restorative effects.

6.4. The Regulatory Framework and the Spanish Context

The comparative analysis presented in Section 5.3 and summarised in Table 3 reveals a fragmented regulatory landscape across European jurisdictions. The countries that have engaged most constructively with the challenge—Germany, the Netherlands, Slovakia, and Switzerland—share a common regulatory architecture: explicit statutory authorisation, a defined scope limited to specific traits, a requirement for prior judicial oversight, and the principle of subsidiarity, under which FDP may be deployed only when conventional methods have been exhausted. These are not merely formal requirements; they are the conditions under which a technology with genuine investigative potential can be deployed without eroding the rights of those it affects.
Spain illustrates the regulatory gap that characterises several of the European jurisdictions examined in this study. Organic Law 10/2007 restricts forensic DNA analysis to non-coding markers for identification purposes and does not address phenotypic prediction. The Eva Blanco case demonstrated that ancestry inference is possible within this framework under judicial authorisation, but it also demonstrated the framework’s limits: the judiciary was required to fill a gap that the legislature had not addressed [44]. The Spanish Ministry of Justice’s 2019 guidelines [70] acknowledged this gap and issued recommendations, judicial authorisation in all instances, restriction to cases without database matches, mandatory training for legal professionals, that have not yet been translated into legislation.
A further consideration specific to the Spanish context is the interaction between the expanded investigative reach of FDP and the statutory prescription periods under the Criminal Code. The most serious offences prescribe after twenty years, which means that even where FDP enables the identification of a perpetrator decades after an offence, criminal prosecution may be time-barred. This tension between forensic capability and legal prescription does not negate the ethical and restorative value of identification, but it points to the need for legislators to consider whether existing frameworks remain appropriate in an era of expanding forensic reach.

6.5. Limitations

Three limitations of this study merit explicit acknowledgement. First, the casework analysis is subject to a confirmatory selection bias. The cases reviewed were selected based on documented positive outcomes, and the operational literature does not currently provide systematic records of cases in which FDP produced inconclusive or misleading results [88]. The absence of negative outcomes from the public record reflects a broader transparency deficit in the forensic industry, one that significantly constrains balanced evaluation of phenotyping efficacy. The development of standardised reporting frameworks that require documentation of both successful and unsuccessful applications, analogous to adverse event reporting in clinical medicine, should be a research and policy priority. A further limitation is structural rather than bibliographic. The inclusion criterion requiring definitive identification means that cases where FDP was used but the investigation remained unresolved cannot enter the analysis. This constrains what can be concluded about operational effectiveness: the cases reviewed show only instances where FDP contributed to a confirmed outcome, not the full range of situations in which it has been deployed. Second, the geographical scope of the casework analysis is primarily drawn from United States, where operational deployment has been most extensively documented, with one additional case from the United Kingdom (Operation Minstead). The legal, institutional, and demographic conditions in the United States differ substantially from those prevailing in European jurisdictions, and the findings cannot be directly extrapolated to the European context that this study also addresses. The inclusion of European casework, as systematic documentation becomes available, would considerably strengthen the comparative dimensions of future research. Third, the Snapshot system from Parabon NanoLabs®, Inc. (Reston, VA, USA) operates without published technical details or independent peer-reviewed validation. The accuracy of the phenotypic predictions underlying the cases reviewed cannot therefore be independently verified. Qualitative concordance between predicted profiles and confirmed appearances is noted in several cases, but this observation rests on descriptive reporting rather than quantitative validation.

7. Conclusions

Forensic DNA phenotyping has moved from scientific possibility to operational reality. The evidence reviewed in this study demonstrates a consistent pattern: where conventional law enforcement genetic databases have failed, phenotypic analysis has in documented cases provided the investigative thread that led, ultimately, to identification. In doing so, it has restored something that cold cases systematically deny, the possibility of responsibility, and for the families of victims, the prospect of truth after years of uncertainty. These outcomes are not merely forensic achievements: examined through the frameworks of deterrence theory and restorative justice, they represent a contribution to purposes that lie at the heart of criminal justice itself.
The same evidence, however, exposes the conditions under which that contribution remains partial and uneven. Phenotypic predictions are probabilistic, not identificatory. Accuracy varies substantially across trait categories and is systematically lower for non-European populations. The most widely deployed commercial system operates without published validation. And across several of the jurisdictions examined, including Spain, no explicit legal framework governs its use. The result is a technology with genuine and documented potential, deployed in a legal and scientific environment that is not yet equipped to accommodate it responsibly. Addressing this gap requires progress on three fronts simultaneously.

7.1. Scientific Priorities

The most urgent scientific need is the diversification of GWAS reference cohorts to include non-European and admixed populations. The current accuracy gap is not an inherent limitation of FDP as a technology; it is a consequence of historical underrepresentation in research cohorts, and it is correctable. Alongside this, independent peer-reviewed validation of commercially deployed systems, particularly those that currently operate without published technical documentation, is a prerequisite for responsible operational use. Facial morphology and other complex polygenic traits require sustained research investment, but progress should not come at the expense of rigorous validation of the systems already in use.

7.2. Transparency and Reporting Standards

The absence of systematic reporting on unsuccessful or inconclusive FDP applications is a serious limitation on the field’s ability to evaluate itself honestly. Standardised reporting frameworks, requiring documentation of both positive and negative outcomes, and publicly available to the research community, would transform the evidence base and enable the kind of balanced evaluation that policy decisions in this area require. Transparency is not a bureaucratic requirement; in a criminal justice context, it is a precondition for accountability.

7.3. Legislative Reform

The most urgent practical need is legislative action. The comparative evidence reviewed in this study demonstrates that targeted constitutional frameworks are both feasible and effective: Germany, the Netherlands, Slovakia, and Switzerland have shown that it is possible to authorise the use of FDP for specific investigative purposes whilst maintaining proportionality, judicial oversight, and fundamental rights protections. Several of the European jurisdictions examined in this study, including Spain, have yet to take this step. In the meantime, the technology is already being deployed—through judicial precedent, investigative practice, and institutional discretion—in the absence of any formal framework. The costs of that absence fall disproportionately on those already most exposed to the criminal justice system. Legislative action is not optional; it is overdue.

Author Contributions

Conceptualisation, L.H.-O. and C.G.; Methodology, L.H.-O.; Investigation, L.H.-O. and C.G.; Data Curation, L.H.-O. and C.G.; Writing—Original Draft Preparation, L.H.-O.; Writing—Review & Editing, L.H.-O. and C.G.; Supervision, C.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Data Availability Statement

The search strategy and inclusion criteria are detailed in Section 3. All sources evaluated in this review, alongside the primary legal documents cited in the comparative analysis, are publicly available and identified in the reference list.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Beccaria, C. Beccaria: “On Crimes and Punishments” and Other Writings; Bellamy, R., Ed.; Cambridge Texts in the History of Political Thought; Cambridge University Press: Cambridge, UK, 1995; ISBN 978-0-521-47982-0. [Google Scholar]
  2. Becker, G.S. Crime and Punishment: An Economic Approach. J. Polit. Econ. 1968, 76, 169–217. [Google Scholar] [CrossRef] [Scilit]
  3. Nagin, D.S. Deterrence in the Twenty-First Century. Crime. Justice 2013, 42, 199–263. [Google Scholar] [CrossRef] [Scilit]
  4. Braithwaite, J. Crime, Shame and Reintegration; Cambridge University Press: Cambridge, UK, 1989; ISBN 978-0-521-35668-8. [Google Scholar]
  5. Zehr, H. Changing Lenses: A New Focus for Crime and Justice; Herald Press: Scottdale, PA, USA, 2007; ISBN 978-0-8361-3512-1. [Google Scholar]
  6. Bell, S.; Butler, J.M. Understanding Forensic DNA; Cambridge University Press: Cambridge, UK, 2022; ISBN 978-1-009-04986-3. [Google Scholar]
  7. Carey, G. Human Genetics for the Social Sciences; SAGE: Thousand Oaks, CA, USA, 2003; ISBN 978-0-7619-2345-9. [Google Scholar]
  8. Butler, J.M. Fundamentals of Forensic DNA Typing; Academic Press: San Diego, CA, USA, 2009; ISBN 978-0-08-096176-7. [Google Scholar]
  9. Ambers, A. Forensic Genetic Approaches for Identification of Human Skeletal Remains, 1st ed.; Academic Press: San Diego, CA, USA, 2022; ISBN 978-0-12-815766-4. [Google Scholar]
  10. Alonso, A. Conceptos Bbásicos de ADN Forense; Centro de Estudios Jurídicos: Madrid, Spain, 2004. [Google Scholar]
  11. Schneider, P.M. Scientific Standards for Studies in Forensic Genetics. Forensic Sci. Int. 2007, 165, 238–243. [Google Scholar] [CrossRef] [Scilit]
  12. Elkins, K.M.; Garloff, A.T.; Zeller, C.B. Additional Predictions for Forensic DNA Phenotyping of Externally Visible Characteristics Using the ForenSeq and Imagen Kits. J. Forensic Sci. 2023, 68, 608–613. [Google Scholar] [CrossRef] [Scilit]
  13. Mahna, D.; Dutt, M.; Puri, S.; Kaur, T.; Sharma, S. Forensic DNA Phenotyping. In Forensic DNA Typing: Principles, Applications and Advancements; Shrivastava, P., Dash, H.R., Lorente, J.A., Imam, J., Eds.; Springer: Singapore, 2020; pp. 547–559. ISBN 978-981-15-6655-4. [Google Scholar]
  14. Podini, D.; Gettings, K.B. Forensic Analysis of Externally Visible Characteristics: Phenotyping. In Forensic DNA Analysis; Apple Academic Press: Palm Bay, FL, USA, 2021. [Google Scholar]
  15. Cha, S.; Lim, J.E.; Park, A.Y.; Do, J.-H.; Lee, S.W.; Shin, C.; Cho, N.H.; Kang, J.-O.; Nam, J.M.; Kim, J.-S.; et al. Identification of Five Novel Genetic Loci Related to Facial Morphology by Genome-Wide Association Studies. BMC Genom. 2018, 19, 481. [Google Scholar] [CrossRef] [Scilit]
  16. Shaffer, J.R.; Orlova, E.; Lee, M.K.; Leslie, E.J.; Raffensperger, Z.D.; Heike, C.L.; Cunningham, M.L.; Hecht, J.T.; Kau, C.H.; Nidey, N.L.; et al. Genome-Wide Association Study Reveals Multiple Loci Influencing Normal Human Facial Morphology. PLoS Genet. 2016, 12, e1006149. [Google Scholar] [CrossRef] [Scilit]
  17. Adhikari, K.; Fuentes-Guajardo, M.; Quinto-Sánchez, M.; Mendoza-Revilla, J.; Camilo Chacón-Duque, J.; Acuña-Alonzo, V.; Jaramillo, C.; Arias, W.; Lozano, R.B.; Pérez, G.M.; et al. A Genome-Wide Association Scan Implicates DCHS2, RUNX2, GLI3, PAX1 and EDAR in Human Facial Variation. Nat. Commun. 2016, 7, 11616. [Google Scholar] [CrossRef] [Scilit]
  18. White, J.D.; Indencleef, K.; Naqvi, S.; Eller, R.J.; Hoskens, H.; Roosenboom, J.; Lee, M.K.; Li, J.; Mohammed, J.; Richmond, S.; et al. Insights into the Genetic Architecture of the Human Face. Nat. Genet. 2021, 53, 45–53. [Google Scholar] [CrossRef] [Scilit]
  19. Kayser, M.; Branicki, W.; Parson, W.; Phillips, C. Recent Advances in Forensic DNA Phenotyping of Appearance, Ancestry and Age. Forensic Sci. Int. Genet. 2023, 65, 102870. [Google Scholar] [CrossRef] [Scilit]
  20. Fujimoto, A.; Ohashi, J.; Nishida, N.; Miyagawa, T.; Morishita, Y.; Tsunoda, T.; Kimura, R.; Tokunaga, K. A Replication Study Confirmed the EDAR Gene to Be a Major Contributor to Population Differentiation Regarding Head Hair Thickness in Asia. Hum. Genet. 2008, 124, 179–185. [Google Scholar] [CrossRef] [Scilit][Green Version]
  21. Walsh, S.; Liu, F.; Ballantyne, K.N.; van Oven, M.; Lao, O.; Kayser, M. IrisPlex: A Sensitive DNA Tool for Accurate Prediction of Blue and Brown Eye Colour in the Absence of Ancestry Information. Forensic Sci. Int. Genet. 2011, 5, 170–180. [Google Scholar] [CrossRef] [Scilit]
  22. Walsh, S.; Liu, F.; Wollstein, A.; Kovatsi, L.; Ralf, A.; Kosiniak-Kamysz, A.; Branicki, W.; Kayser, M. The HIrisPlex System for Simultaneous Prediction of Hair and Eye Colour from DNA. Forensic Sci. Int. Genet. 2013, 7, 98–115. [Google Scholar] [CrossRef] [Scilit]
  23. Rees, J.L. The Melanocortin 1 Receptor (MC1R): More Than Just Red Hair. Pigment Cell Res. 2000, 13, 135–140. [Google Scholar] [CrossRef] [Scilit]
  24. Cho, H.-W.; Jin, H.-S.; Eom, Y.-B. FGFRL1 and FGF Genes Are Associated with Height, Hypertension, and Osteoporosis. PLoS ONE 2022, 17, e0273237. [Google Scholar] [CrossRef] [Scilit]
  25. Lettre, G. Recent Progress in the Study of the Genetics of Height. Hum. Genet. 2011, 129, 465–472. [Google Scholar] [CrossRef] [Scilit]
  26. Yang, T.-L.; Guo, Y.; Zhang, L.-S.; Tian, Q.; Yan, H.; Guo, Y.-F.; Deng, H.-W. HMGA2 Is Confirmed to Be Associated with Human Adult Height. Ann. Hum. Genet. 2010, 74, 11–16. [Google Scholar] [CrossRef] [Scilit]
  27. Chen, Y.; Hysi, P.; Maj, C.; Heilmann-Heimbach, S.; Spector, T.D.; Liu, F.; Kayser, M. Genetic Prediction of Male Pattern Baldness Based on Large Independent Datasets. Eur. J. Hum. Genet. 2023, 31, 321–328. [Google Scholar] [CrossRef] [Scilit]
  28. Hillmer, A.M.; Hanneken, S.; Ritzmann, S.; Becker, T.; Freudenberg, J.; Brockschmidt, F.F.; Flaquer, A.; Freudenberg-Hua, Y.; Jamra, R.A.; Metzen, C.; et al. Genetic Variation in the Human Androgen Receptor Gene Is the Major Determinant of Common Early-Onset Androgenetic Alopecia. Am. J. Hum. Genet. 2005, 77, 140–148. [Google Scholar] [CrossRef] [Scilit]
  29. Huang, C.; Chen, W.; Wang, X. Studies on the Fat Mass and Obesity-Associated (FTO) Gene and Its Impact on Obesity-Associated Diseases. Genes Dis. 2023, 10, 2351–2365. [Google Scholar] [CrossRef] [Scilit]
  30. Kim, H.S.; Lee, I.K.; Suh, Y.S. Polymorphism of Melanocortin-4 Receptor and Obesity. Diabetes Metab. J. 2003, 27, 123–131. [Google Scholar] [CrossRef] [Scilit]
  31. Lotta, L.A.; Mokrosiński, J.; de Oliveira, E.M.; Li, C.; Sharp, S.J.; Luan, J.; Brouwers, B.; Ayinampudi, V.; Bowker, N.; Kerrison, N.; et al. Human Gain-of-Function MC4R Variants Show Signaling Bias and Protect against Obesity. Cell 2019, 177, 597–607.e9. [Google Scholar] [CrossRef] [Scilit]
  32. Azrida, R.; Suryani, F.; Alma, B.; Sanjaya, S.; Anwar, K. Forensic DNA Phenotyping for Predicting Externally Visible Characteristics in Indonesian Populations: A Novel Tool for Criminal Investigations. Sriwij. J. Forensic Medicolegal 2024, 2, 64–77. [Google Scholar] [CrossRef] [Scilit]
  33. Fabbri, M.; Alfieri, L.; Mazdai, L.; Frisoni, P.; Gaudio, R.M.; Neri, M. Application of Forensic DNA Phenotyping for Prediction of Eye, Hair and Skin Colour in Highly Decomposed Bodies. Healthcare 2023, 11, 647. [Google Scholar] [CrossRef] [Scilit]
  34. Kayser, M. Forensic DNA Phenotyping: Predicting Human Appearance from Crime Scene Material for Investigative Purposes. Forensic Sci. Int. Genet. 2015, 18, 33–48. [Google Scholar] [CrossRef] [Scilit]
  35. Marano, L.A.; Fridman, C. DNA Phenotyping: Current Application in Forensic Science. Res. Rep. Forensic Med. Sci. 2019, 9, 1–8. [Google Scholar] [CrossRef] [Scilit]
  36. Tozzo, P.; Politi, C.; Delicati, A.; Gabbin, A.; Caenazzo, L. External Visible Characteristics Prediction through SNPs Analysis in the Forensic Setting: A Review. Front. Biosci.-Landmark 2021, 26, 828. [Google Scholar] [CrossRef] [Scilit]
  37. Fondevila, M.; Phillips, C.; Lareu, M. Aplicaciones no convencionales de marcadores bialélicos (SNPs) en genética forense. Bol. Galego Med. Leg. Forense 2014, 20, 21–29. [Google Scholar]
  38. Pontes, M.L.; Medeiros, R. Autosomal SNPs in Different Forensic Applications. Aust. J. Forensic Sci. 2016, 48, 248–256. [Google Scholar] [CrossRef] [Scilit]
  39. Terrado-Ortuño, N.; May, P. Forensic DNA Phenotyping: A Review on SNP Panels, Genotyping Techniques, and Prediction Models. Forensic Sci. Res. 2025, 10, owae013. [Google Scholar] [CrossRef] [Scilit]
  40. Brancato, D.; Coniglio, E.; Bruno, F.; Agostini, V.; Saccone, S.; Federico, C. Forensic DNA Phenotyping: Genes and Genetic Variants for Eye Color Prediction. Genes 2023, 14, 1604. [Google Scholar] [CrossRef] [Scilit]
  41. Browne, T.N.; Freeman, M. Next Generation Sequencing: Forensic Applications and Policy Considerations. WIREs Forensic Sci. 2024, 6, e1531. [Google Scholar] [CrossRef] [Scilit]
  42. Carratto, T.M.T.; Guimarães de Oliveira, M.L.; Mendes-Junior, C.T. Chapter 16 - Forensic DNA Phenotyping in the next-Generation Sequencing Era. In Next Generation Sequencing (NGS) Technology in DNA Analysis; Dash, H.R., Elkins, K.M., Al-Snan, N.R., Eds.; Academic Press: San Diego, CA, USA, 2024; pp. 311–336. ISBN 978-0-323-99144-5. [Google Scholar]
  43. Schneider, P.M.; Prainsack, B.; Kayser, M. The Use of Forensic DNA Phenotyping in Predicting Appearance and Biogeographic Ancestry. Dtsch. Ärztebl. Int. 2019, 116, 873–880. [Google Scholar] [CrossRef] [Scilit]
  44. Canales Serrano, A. El fenotipado de ADN como potencial herramienta investigativa en el campo de la genética forense. Estado actual. Rev. Esp. Med. Leg. 2020, 46, 183–190. [Google Scholar] [CrossRef] [Scilit]
  45. MacLean, C.E.; Lamparello, A. Forensic DNA Phenotyping in Criminal Investigations and Criminal Courts: Assessing and Mitigating the Dilemmas Inherent in the Science. Recent Adv. DNA Gene Seq. Former. Recent Pat. DNA Gene Seq. 2014, 8, 104–112. [Google Scholar] [CrossRef] [Scilit]
  46. Bitarello, B.D.; Mathieson, I. Polygenic Scores for Height in Admixed Populations. G3 GenesGenomesGenetics 2020, 10, 4027–4036. [Google Scholar] [CrossRef] [Scilit]
  47. Flores-López, B.; López-Ceballos, A.; López-Aguilar, C.; Rico-Méndez, M.; Acosta-Ramírez, K.; Cano-Ravell, A.; Gembe-Olivarez, G.; López-Quintero, A.; Aguilar-Velázquez, J.; Ramírez-de-Arellano Sánchez, J.; et al. Genetic Prediction of Eye, Hair, and Skin Color: Forensic Applications and Challenges in Latin American Populations. Genes 2025, 16, 1227. [Google Scholar] [CrossRef] [Scilit]
  48. Salvo, N.M.; Janssen, K.; Kirsebom, M.K.; Meyer, O.S.; Berg, T.; Olsen, G.-H. Predicting Eye and Hair Colour in a Norwegian Population Using Verogen’s ForenSeqTM DNA Signature Prep Kit. Forensic Sci. Int. Genet. 2022, 56, 102620. [Google Scholar] [CrossRef] [Scilit]
  49. Caliebe, A.; Bruder, L.; Riege, J.; Seidel, M. Evaluation of the Prediction Potential of the HIrisPlex-S System in a North German Population. Genes 2026, 17, 452. [Google Scholar] [CrossRef] [Scilit]
  50. Chaitanya, L.; Breslin, K.; Zuñiga, S.; Wirken, L.; Pośpiech, E.; Kukla-Bartoszek, M.; Sijen, T.; de Knijff, P.; Liu, F.; Branicki, W.; et al. The HIrisPlex-S System for Eye, Hair and Skin Colour Prediction from DNA: Introduction and Forensic Developmental Validation. Forensic Sci. Int. Genet. 2018, 35, 123–135. [Google Scholar] [CrossRef] [Scilit]
  51. Kushwaha, P.; Ahmed, U.; Rana, M. Forensic DNA Phenotyping: A Promising Tool to Predict Human Appearance for Forensic Purposes. GSC Biol. Pharm. Sci. 2023, 23, 34–41. [Google Scholar] [CrossRef] [Scilit]
  52. Phillips, C.; Rodriguez, A.; Gómez-Tato, A.; Álvarez-Dios, J.; de Cal, M.C.; Salas, A.; Carracedo, Á.; Lareu, M.V. DNA Tests for Ancestry and Phenotype Inference Applied to the UK Metropolitan Police Operation Minstead: The Investigation of Serial Sex Offender Delroy Grant. Forensic Sci. Int. Genet. 2026, 85, 103527. [Google Scholar] [CrossRef] [Scilit]
  53. González-Ortiz, N.; Guardado-Estrada, M.; Zepeta-Flores, N.; Moreno-Ortiz, J.M.; Ramírez-de-Arellano, A.; Rangel-Villalobos, H.; Muñoz-Valle, J.F.; Aguilar-Velázquez, J.A. Performance of the ForenSeqTM Imagen Kit for Forensic DNA Phenotyping Under Partial Genotyping Conditions. Genes 2026, 17, 354. [Google Scholar] [CrossRef] [Scilit]
  54. Diepenbroek, M.; Bayer, B.; Anslinger, K. Pushing the Boundaries: Forensic DNA Phenotyping Challenged by Single-Cell Sequencing. Genes 2021, 12, 1362. [Google Scholar] [CrossRef] [Scilit]
  55. Pardo-Seco, J.; Martinón-Torres, F.; Salas, A. Evaluating the Accuracy of AIM Panels at Quantifying Genome Ancestry. BMC Genom. 2014, 15, 543. [Google Scholar] [CrossRef] [Scilit]
  56. Marcante, B.; Marino, L.; Cattaneo, N.E.; Delicati, A.; Tozzo, P.; Caenazzo, L. Advancing Forensic Human Chronological Age Estimation: Biochemical, Genetic, and Epigenetic Approaches from the Last 15 Years: A Systematic Review. Int. J. Mol. Sci. 2025, 26, 3158. [Google Scholar] [CrossRef] [Scilit]
  57. Vidaki, A.; Ballard, D.; Aliferi, A.; Miller, T.H.; Barron, L.P.; Syndercombe Court, D. DNA Methylation-Based Forensic Age Prediction Using Artificial Neural Networks and next Generation Sequencing. Forensic Sci. Int. Genet. 2017, 28, 225–236. [Google Scholar] [CrossRef] [Scilit]
  58. Gerra, M.C.; Dallabona, C.; Cecchi, R. Epigenetic Analyses in Forensic Medicine: Future and Challenges. Int. J. Leg. Med. 2024, 138, 701–719. [Google Scholar] [CrossRef] [Scilit]
  59. Beentjes, I.; Haagmans, M.A.; De Bruin, D.D.S.H.; Permana, A.; Pośpiech, E.; Branicki, W.; M’charek, A.A.; Van Der Gaag, K.J.; Sijen, T.; Henneman, P. DNA Methylation-Based Forensic Framework for Age Prediction and Body Fluid Identification Using Nanopore Sequencing. Forensic Sci. Int. Genet. 2026, 81, 103370. [Google Scholar] [CrossRef] [Scilit]
  60. Vidaki, A.; Kayser, M. Recent Progress, Methods and Perspectives in Forensic Epigenetics. Forensic Sci. Int. Genet. 2018, 37, 180–195. [Google Scholar] [CrossRef] [Scilit]
  61. Vidaki, A.; Kayser, M. From Forensic Epigenetics to Forensic Epigenomics: Broadening DNA Investigative Intelligence. Genome Biol. 2017, 18, 238. [Google Scholar] [CrossRef] [Scilit]
  62. Sabeeha; Hasnain, S.E. Forensic Epigenetic Analysis: The Path Ahead. Med. Princ. Pract. 2019, 28, 301–308. [Google Scholar] [CrossRef] [Scilit]
  63. Silva, D.S.B.S.; Ecker, H.; Walcott, J.; Weeden, R.; Medina, A.; Gorson, J.M. Analysis of DNA Methylation Markers for Tissue Identification in Individuals with Different Clinical Phenotypes. Electrophoresis 2023, 44, 1037–1046. [Google Scholar] [CrossRef] [Scilit]
  64. Yuan, M.; Goovaerts, S.; Lee, M.K.; Devine, J.; Richmond, S.; Walsh, S.; Shriver, M.D.; Shaffer, J.R.; Marazita, M.L.; Peeters, H.; et al. Optimized Phenotyping of Complex Morphological Traits: Enhancing Discovery of Common and Rare Genetic Variants. Brief. Bioinform. 2025, 26, bbaf090. [Google Scholar] [CrossRef] [Scilit]
  65. Benítez Boldo, A. De La Ciencia a La Sociedad: Implicaciones Psicológicas y Criminológicas Del Fenotipado Forense de ADN (FDP). Edupsykhé Rev. Psicol. Educ. 2026, 23, 44–60. [Google Scholar] [CrossRef] [Scilit]
  66. Bundesrepublik Deutschland. Strafprozessordnung (StPO); §81e; Bundesrepublik Deutschland: Berlin, Germany, 2019; p. 2121. [Google Scholar]
  67. Koninkrijk der Nederlanden. Wet DNA-Onderzoek Bij Veroordeelden; Nederlandse Overheid: The Hague, The Netherlands, 2003; p. 201.
  68. Národná rada Slovenskej Republiky. Zákon č. 417/2002 Z. z. o Využívaní Analýzy Deoxyribonukleovej Kyseliny Na Identifikáciu Osôb; Národná rada Slovenskej Republiky: Bratislava, Slovakia, 2002.
  69. Schweizerische Eidgenossenschaft. Bundesgesetz Über Die Verwendung von DNA-Profilen Im Strafverfahren und Zur Identifizierung von Unbekannten Oder Vermissten Personen (DNA-Profil-Gesetz); Schweizerische Eidgenossenschaft: Bern, Switzerland, 2024.
  70. Jefatura del Estado. Ley Orgánica 10/2007, de 8 de Octubre, Reguladora de La Base de Datos Policial Sobre Identificadores Obtenidos a Partir Del ADN; Boletín Oficial del Estado (BOE): Madrid, Spain, 2007; pp. 40969–40972.
  71. Assembleia da República. Lei n.º 5/2008, de 12 de Fevereiro, Que Aprova a Criação de Uma Base de Dados de Perfis de ADN Para Fins de Identificação Civil e Criminal; Imprensa Nacional-Casa da Moeda (INCM): Lisbon, Portugal, 2008; p. 30.
  72. Chambre des Représentants de Belgique. Loi Du 7 Mars 2024 Modifiant Diverses Dispositions Relatives à l’analyse d’ADN En Matière Pénale; Moniteur Belge: Brussels, Belgium, 2024.
  73. Samuel, G.; Prainsack, B. Civil Society Stakeholder Views on Forensic DNA Phenotyping: Balancing Risks and Benefits. Forensic Sci. Int. Genet. 2019, 43, 102157. [Google Scholar] [CrossRef] [Scilit]
  74. Gareau-Léonard, A.; Mousseau, V.; Crispino, F.; Milot, E. Forensic DNA Phenotyping: Examining Knowledge and Operational View from Police Officers. Forensic Sci. Int. Synerg. 2025, 10, 100586. [Google Scholar] [CrossRef] [Scilit]
  75. Cooper, G.S.; Meterko, V. Cognitive Bias Research in Forensic Science: A Systematic Review. Forensic Sci. Int. 2019, 297, 35–46. [Google Scholar] [CrossRef] [Scilit]
  76. Elaad, E. Tunnel Vision and Confirmation Bias Among Police Investigators and Laypeople in Hypothetical Criminal Contexts. Sage Open 2022, 12, 21582440221095022. [Google Scholar] [CrossRef] [Scilit]
  77. Hopman, R. Opening up Forensic DNA Phenotyping: The Logics of Accuracy, Commonality and Valuing. New Genet. Soc. 2020, 39, 424–440. [Google Scholar] [CrossRef] [Scilit]
  78. Coquet, M.; Terrado-Ortuño, N. Forensic DNA Phenotyping: Privacy Breach, Bias Reification and the Pitfalls of Abstract Assessments of Rights. Int. J. Police Sci. Manag. 2023, 25, 262–279. [Google Scholar] [CrossRef] [Scilit]
  79. Scudder, N.; McNevin, D.; Kelty, S.F.; Walsh, S.J.; Robertson, J. Forensic DNA Phenotyping: Developing a Model Privacy Impact Assessment. Forensic Sci. Int. Genet. 2018, 34, 222–230. [Google Scholar] [CrossRef] [Scilit]
  80. Queirós, F. The Visibilities and Invisibilities of Race Entangled with Forensic DNA Phenotyping Technology. J. Forensic Leg. Med. 2019, 68, 101858. [Google Scholar] [CrossRef] [Scilit]
  81. Granja, R.; Machado, H. Forensic DNA Phenotyping and Its Politics of Legitimation and Contestation: Views of Forensic Geneticists in Europe. Soc. Stud. Sci. 2023, 53, 850–868. [Google Scholar] [CrossRef] [Scilit]
  82. Zieger, M. Forensic DNA Phenotyping in Europe: How Far May It Go? J. Law Biosci. 2022, 9, lsac024. [Google Scholar] [CrossRef] [Scilit]
  83. Van Camp, N.; Dierickx, K. The Retention of Forensic DNA Samples: A Socio-Ethical Evaluation of Current Practices in the EU. J. Med. Ethics 2008, 34, 606–610. [Google Scholar] [CrossRef] [Scilit]
  84. Sauvagère, S.; Bougerie, M.; Hermitte, F.; Hubac, S.; Manivet, P.; Kheris, S.; Duby, V.; Boissonneau, N.; Siatka, C. Recreational Genetic Databases, Artificial Intelligence, and Forensic Genetics: Technical Advances, Legal Challenges, and Bioethical Perspectives. Genes 2026, 17, 730. [Google Scholar] [CrossRef] [Scilit]
  85. ISO/IEC 17025:2017; General Requirements for the Competence of Testing and Calibration Laboratories. International Organization for Standardization (ISO): Geneva, Switzerland, 2017.
  86. Abdelaal, G.M.M.; Pal, S.K. Forensic DNA Phenotyping: The Need for Proportionate Regulation and Judicial Clarity in Law Enforcement. Egypt. J. Forensic Sci. 2026, 16, 36. [Google Scholar] [CrossRef] [Scilit]
  87. Zieger, M.; Scudder, N. Ethical and Legal Reflections on Secondary Research Using Genetic Data Acquired for Criminal Investigation Purposes. Forensic Sci. Int. Genet. 2025, 75, 103178. [Google Scholar] [CrossRef] [Scilit]
  88. Atwood, L.; Raymond, J.; Sears, A.; Bell, M.; Daniel, R. From Identification to Intelligence: An Assessment of the Suitability of Forensic DNA Phenotyping Service Providers for Use in Australian Law Enforcement Casework. Front. Genet. 2021, 11, 568701. [Google Scholar] [CrossRef] [Scilit]
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