Forensic Sciences

Forensic anthropologists build a biological profile—consisting of sex, age, population affinity, and stature estimates—to assist medicolegal stakeholders in the identification of unknown human skeletal remains. While adult age-at-death estimations can narrow the pool of potential individuals, a lack of standards, best practices, and consensus among anthropologists for method selection and the production of a final age estimate present significant challenges. The purpose of this research is to identify age-reporting strategies that provide the most accurate and reliable (i.e., low inaccuracy and low bias) adult age-at-death estimates when evaluated considering the total sample, age cohort (20–39; 40–59; 60–79), and sex. Age-reporting strategies in this study were derived from six age-at-death estimation methods and tested on 58 adult individuals (31 males, 27 females) from the UTK Donated Skeletal Collection. An experienced-based estimation strategy was also assessed. A paired-samples t-test was used to determine whether there was a significant difference (p ≤ 0.05) between the mean estimated age and the actual age for all age-reporting strategies. Results show that the most accurate and reliable age-reporting strategy varied if the sample was evaluated as a whole, by age, or by sex. While none of the age-reporting strategies evaluated in this study were consistently the most accurate and reliable for all of the sample categories, the experience-based approach performed well for each group. Full article

Forensic sciences aggregate a series of scientific and technological domains that aid the judiciary and judicial system. Despite the highly specialized and qualified professionals taking a role in forensic practice, this paradigmatic integration of law, science, and technology often leads them to face significant ethical challenges. Indeed, forensic sciences hold a unique position due to the social and legal implications inherent to forensic expertise. The potential interference with personal rights and freedoms requires the professional practice of the forensic specialist to be guided by alignment with scientific-technical competence under the seal of the highest ethical principles. However, the absence of a specific statutory regulation blurs the performance of the forensic professional and may harm the professional credibility but also the scientific domain as a whole. The existence of ethical pillars is essential to support professional practice, following international recommendations in this regard. Herein, we propose a framework for a code of ethics and conduct that is based on the professional particularities characterizing the forensic practice but also considers the ethical issues that are mandatory to ensure high levels of reliability and credibility of forensic specialists. Full article

Age-at-death estimation is influenced by biological and environmental factors. Physiological stress is intertwined with these factors, yet their impact on senescence and age estimation is unknown. Stature, linear enamel hypoplasia (LEH), and antemortem tooth loss (AMTL) in the Hamann–Todd Osteological Collection (n = 297) are used to understand whether physiological stress is related to age estimation inaccuracy using transition analysis (TA). Considering the low socioeconomic status of individuals in the collection, it was expected that many people experienced moderate to severe physiological stressors throughout their lives. Of the sample, 44.1% had at least one LEH, but analyses found no relationship between LEH incidence and TA error. There was no association between stature and TA error for males or females. However, females with at least one LEH had significantly shorter statures (t = 2.412, p = 0.009), but males did not exhibit the same pattern (t = 1.498, p = 0.068). Further, AMTL frequency and TA error were related (r = 0.276, p < 0.001). A partial correlation controlling for age-at-death yielded a correlation coefficient of 0.024 (p = 0.684), suggesting that this relationship is mostly explained by age-at-death. These data suggest that age estimation methods are not significantly affected by physiological stress in this sample, but further investigations are needed to understand how these variables relate to skeletal aging. Full article

Although there are known limited skeletal traits that can be used to estimate age-at-death, an increasing body of literature is addressing this topic. This is particularly true in journals dedicated to forensic anthropology and past population studies. Research has focused mostly on methodological developments, aiming to update and validate age-at-death methods’ accuracy, with recurrent formulation, reformulation, testing, and re-testing of classical methodological approaches in multiple populational datasets and using novel statistical approaches. This paper explores aging research in adults published over the last century, aiming to portray major research agendas and highlight main institutions and co-authorship networks. A comprehensive dataset of bibliometric data from 1225 publications on age-at-death estimation, published between 1890 and October 2022, was used in the analysis. Major results showed that since the 1990s there has been continuous growth in aging research, predominantly by institutions in the United States. However, in the last 2 decades, research contributions from institutions with a wider geographical location were observed. Moreover, the research terms associated with aging are not limited to bone changes. Rather, dental-related changes are major contributors to aging research. Temporal trends suggested changes in research agendas related to terms and institutional co-authorships which may bring more inclusive and accurate-related method developments. Full article

Historically, serial homicide has been defined in various ways by experts. Recently, there have been renewed efforts to arrive at a consensus definition, yet these efforts have not yet been resolved. At the heart of the controversy appears to be the prioritization of either qualitative definitional features, such as offenders’ intentions and motives, or more observable quantitative features, specifically a minimum threshold of completed murders. The present technical note briefly summarizes this controversy before considering new empirical and theoretical research developments. These developments support a definition that includes a three-victim minimum threshold of forensically linked murderers by the same person(s), occurring in separate events over time, wherein a primary motive is often personal gratification (leisure experience). Full article

While a myriad of effective techniques exist to aid in symphyseal age estimation for those 40 years and younger, few offer similar levels of efficacy for those beyond that threshold. Through the application of a novel technique, this study sought to determine whether a closer inspection of degenerative change may help to improve precision in age estimation for post-epiphyseal adults. Results show that the combination of five distinct areas of interest, plus a correction for density, accurately estimated age 87.75% of the time (averaged amongst four observers [spread: 72–100%]) for a subset of 50 living British females. An adjusted R² value of 0.85, an RSME value of 5.62 years, and a PCC value of 0.92 also confirmed the trialed technique to be a good predictor of age for the entirety of the larger female sample (n = 533). Low inaccuracy (3.86 years) and Bias (0.69 years) further indicate that a continuum-based approach, without pre-set phases or ranges, such as was utilized by this research holds the potential to be at least as effective as the currently available methodologies but with the added advantage of allowing for increased variation at the individual level. Age estimation by linear regression, or by simple addition, yielded estimation envelopes (intervals) of 22–23 and 24 years, respectively, which remain narrow enough to be forensically useful while still wide enough to maximize accuracy in mature adults. Full article

This manuscript aims to introduce the Colección Osteológica Subactual de Santiago (COSS), a documented skeletal collection from Santiago, Chile, consisting of 1635 individuals living in low socioeconomic areas of the capital during the late 19th and early 20th centuries. The origin and current state of this collection, as well as the process by which it came to be housed at the University of Chile, is described. As of today, after long efforts for further documentation and improvements on the physical conditions of the collection, biological sex and age-at-death has been documented through burial records for 1198 individuals. Largely studied by Chilean researchers and students, the COSS collection has enabled a great amount of research, while also serving as part of a thriving scholarly community from different disciplines. Finally, discussion around representativeness, legal status and ethical concerns are addressed, highlighting the specific issues faced when working and studying the COSS collection. Full article

In our experience, university students enrolling in health science and forensic science degrees show difficulty in retaining and integrating basic scientific knowledge learned in their first academic year. Furthermore, in the forensic sciences case, many students have oversimplified and unrealistic expectations as a result of the exposure to crime TV shows, internet blogs, and other social media platforms. Our pedagogical proposal is focused on second-year university students, aiming at promoting effective learning and the integration of scientific knowledge from previous courses, in this particular example, molecular and cell biology and biochemistry, with more advanced forensic courses, such as forensic anthropology and odontology. Teams composed of students and tutors from the teaching staff, with the help of dichotomous keys, are challenged to analyze a crime scene and choose the relevant evidence to further investigate, determine the scientific approach, execute the experimental work, interpret the results and, finally, resolve the case. To assess the pedagogical advantages and the receptivity of this project, a survey is to be carried out among students, and respective statistical analysis is also proposed. Finally, we hope this project outline may be adapted to other subjects, and, therefore, be used to address different pedagogical questions in forensic studies. Full article

Forensic authorship profiling aims to extract socio-demographic information about the authors of anonymous texts based on linguistic features found in their written texts. One aspect of such a profile that is not usually considered is an analysis of the author’s personality traits. The present study intends to provide a starting point for research into this area. This will be achieved through the investigation of linguistic features reflective of the conditions of psychopathy and malignant narcissism in 14 personal letters of the killer Jack Unterweger. Previous research in the field of psychology has largely examined “psychopathic” and “narcissistic” language in spoken conversations rather than written ones, or in texts produced for the respective study rather than in naturally occurring texts. The findings of the present study thus diverge from previous findings in some aspects (e.g., the use of first-person pronouns), while they provide support for others (e.g., the incoherence of thoughts and changes in topics). Full article

Background and Objective: Intravenous therapy is widely used in clinics to deliver medications and fluids to patients, and overuse may cause intravenous-infusion-associated circulatory overload (IACO) and death. However, forensic data on deaths from the overuse of intravenous therapy are limited. We performed a retrospective study to identify whether causes of death in forensic practice were associated with IACO. Methods: A total of 572 medical-related cases with a history of intravenous infusion who suffered from injuries or illnesses and died after treatment in hospitals were recruited from two centers of forensic medicine between 2002 and 2018. Results: The results demonstrated that 6.47% of cases (37/572) were exposed to an infusion overdose that resulted in deaths related to IACO, and 43.24% of cases (16/37) had a net fluid retention ranging from 3.0 L/d to 13.8 L/d. The highest case was administered 1.4 L blood products and 13.6 L fluids within 25 h. We observed significant decreases in red blood cells, hematocrit, hemoglobin, and platelets from the time of “on admission” to “before death”, except for white blood cells. Autopsy findings of 16 cases revealed some organ or tissue pathological alterations related to IACO, including pale-yellow liquid overflow under the abdominal epidermis, much transudate in body cavities, and lung edema with a high tissue density and no obvious slurry deposition in the alveolar lumen. Another 21 cases died after a rapid infusion rate ranging from 111 to 293 drops/min, which resulted from viral myocarditis on autopsy. Conclusions: Our data on excessive or irrational use of intravenous therapy indicate a severe circulatory overload, which may eventually result in lethal outcomes. Therefore, the use of improper intravenous therapy should be reduced to ameliorate adverse health consequences during clinical treatment. Full article

In some jurisdictions, race, ancestry, or population affinity have been used for historical and po-litical, rather than biological, reasons in forensic anthropology when identifying individuals. The approach persists even though the genetic and skeletal data clearly demonstrate that human variation does not cluster into these groups. For over 60 years, these methods have consistently performed poorly when independently tested using large samples. By racializing the deceased, these methods have further marginalized the living. However, there is a need in the investigation of genocide and human rights violations to demonstrate that a specific group was targeted. Without relying on the outdated typological concepts of human variation, in this paper we present preliminary results for a method that can be used in a mass grave context to demonstrate that a specific group was targeted. Using samples from two identified reference collections, we created subsamples from one relatively homogeneous collection to model various mass grave scenarios and used the relatively heterogenous sample from the other collection as a reference for com-parison. In scenarios that varied by sample size and sex, it was possible to determine that a specific group was targeted if the sample size in a hypothetical mass grave was greater than 25 for a multi-sex sample, when sex is not known, and a minimum of 14 if sex could be estimated. Full article

Fire investigators have attempted to study fire behaviors through microstructural examination of molten marks on copper wire. However, there have not been many studies on the metallurgical examination of real-world cases. This research examined the surface morphology and microstructure in the longitudinal section of molten marks on copper wire from various fire scenes to explain how they formed and identify the surrounding materials. The results show that the foreign elements discovered via EDS on the surface of molten marks vary depending on their environment. Molten mark microstructures differed even if they were collected from the same fire scene; a distinct microstructure implies different molten mark formations. Moreover, the presence of residual elements in the microstructure indicates the existence of surrounding materials during formation in a fire. Therefore, microstructural diversity and the presence of residual elements may guide fire investigators in explaining the formation of molten marks and the fire environment for fire investigation. Full article

Forensically important blow flies, Diptera: Calliphoridae, are among the first organisms to colonize carrion. After eggs hatch, the larvae of most blow fly species feed in an aggregation or “mass”. While in this mass larvae may experience periods of hypoxia/anoxia, but the tolerance of blow fly larvae to anoxic conditions is poorly studied. We tested the anoxia tolerance of four species of calliphorids (Calliphora vicina, Cochliomyia macellaria, Lucilia sericata, and Phormia regina), by examining actively feeding third-stage larvae across five temperatures. Experiments were conducted by exposing larvae to pure nitrogen environments and determining mortality at set time intervals. All species show significant linear relationships between survival time and temperature under anoxic conditions. Of species tested, C. macellaria had the greatest tolerance to anoxia (LT₅₀ of 9 h at 20 °C). In contrast, C. vicina was the least tolerant (LT₅₀ of 2.2 h at 40 °C). With all species, survivorship decreased with increasing temperature. Unlike many other insects tested in severe hypoxia, the larvae of the calliphorids tested, which included members of three subfamilies, were not tolerant of anoxic conditions. From these findings, it seems likely that hypoxia is a significant limitation for maggots in a maggot mass, particularly when the mass temperature is high (>40 °C). Forensically, these data provide a limit on potential maggot survival on bodies that have been submerged or otherwise experience severe hypoxia before discovery. Full article

Wildlife forensics is a science field with a remarkable potential to provide accurate information regarding nature conservation and One Health. Wildlife crimes are now a persistent target of public opinion and the concern of conservation professionals, which is constantly putting pressure on governmental and non-governmental entities. Moreover, the cross-species transmission of pathogens is becoming more and more frequent, endangering the interconnected health of humans, animals and the environment (One Health). This review intends to briefly present and illustrate the potential of wildlife forensic sciences not only in crime solving, but also regarding health sciences and species conservation. By allowing target species identification, recreating the crime scene, and considering their contribution to diseases and ecosystems’ surveillance, wildlife forensics are now constantly developing and improving. A cooperative and multidisciplinary approach (with the inclusion of forensic sciences) is necessary to avoid wildlife crimes, disease outbreaks, environmental disasters and to promote a sustainable and healthy future for all the living beings. Full article

Microscopy slides are routinely created as part of sexual assault workflows for screening purposes and retained indefinitely with instances, such as cold cases, where they are the only remaining source of evidence. To date, no method has been developed to harvest the cells from these slides for differential extraction using the i-sep^® DL column or Intimate extraction using the PrepFiler™ Express chemistry supplemented with 60 mM DTT. This study used mock sexual assault slides from 2010 to develop a potential cell harvesting method, then tested both the extraction methods on historic casework slides collected in the 1980s and 1990s. Key findings included the necessity to re-screen slides microscopically to assess current cellular loading and the utility of using phase contrast to enhance visualisation of spermatozoa on historic slides. Both extraction methods successfully recovered DNA and generated partial profiles from the 1990s slides, but 1980s slides were too degraded to provide informative profiles. Differential extraction provided additional contextual information by separating contributors into sperm and non-sperm fractions, resulting in cleaner sperm profiles for interpretation. The study successfully established methods for historic microscope slides to be used as viable sources of evidence, potentially aiding in the progression and resolution of sexual assault investigations. Full article

The estimation of biological sex is of paramount relevance in the analysis of skeletal remains recovered in forensic contexts. This study aims to assess sexual dimorphism for identification purposes, from two reference samples of the Portuguese population, and a depiction of the size- and shape-related sexual dimorphism of the human scapula using geometric morphometrics approaches. The sample comprised 211 individuals (100 males and 111 females). A generalized Procrustes analysis (GPA) was performed for shape analyses, a principal component analysis (PCA) and a Procrustes ANOVA were implemented on the GPA transformed variables, and a discriminant analysis was used to assess the cross-validated accuracy of sex estimates. The data showed that male scapulae were larger, with medial and lateral curves more pronounced and an inferior angle more acute than females. The males and females were classified with low accuracy (66.82% and 65.88% for landmarks and semi-landmarks data) based on shape. Combining size and shape variables improved the accuracy of the prediction using landmarks data (80.09%). A combination of both variables might improve the chances of the geometric morphometrics methodology in correctly estimating the sex of unidentified individuals, especially if the skeletal elements show low sexual shape dimorphism. Full article

The mixed cumulative probit (MCP), a new, flexible algorithm that accommodates a variety of mean and shape parameters in univariate models and conditional dependence/independence in multivariate models, was used to develop subadult age estimation models. Sixty-two variables were collected on computed tomography (CT) images of 1317 individuals (537 females and 780 males) aged between birth and 21 years from the United States sample in the Subadult Virtual Anthropology Database (SVAD). Long bone measurements (n = 18), stages of epiphyseal fusion and ossification (n = 28), and stages of dental development of permanent teeth (n = 16) were used in univariate, multivariate, and mixed models and compared using test mean log posterior (TMNLP), root mean squared error (RMSE), and percent accuracy on an independent test sample. Out of the six possible parameter combinations, all combinations were accounted for at least once in the data and conditionally dependent models outperformed the conditionally independent models. Overall, multivariate models exhibited smaller TMNLP and RMSE, and an overall greater stability in the age estimations compared to univariate models across all ages and independent of indicator type. Pre-optimized subadult age estimation models are freely available for immediate application through MCP-S-Age, a graphical user interface. Full article

Decompositional processes depend on temperature, humidity, and light, as well as on animals that can access the body. In low-level cases, suicides, or cases of self-neglect especially, these factors are not always taken into consideration because a full investigation may not have taken place. Misinterpretations of environmental factors can put crime scene investigators on the wrong track, and natural causes of missing tissue may be wrongly interpreted as violence or wounds. Here, we give some examples for the influence of invertebrate land animals on corpses. Full article