Sodium Nitrite-Related Fatalities: Are We Facing a New Trend? Case Report and Literature Review

Abstract

Suicide is a public health concern worldwide. The methods used worldwide can vary based on geographical context and the ease with which victims can find the means to act on suicidal thoughts. In this context, the recent emergence of an online market for toxic and narcotic substances has increased accessibility to these substances for recreational and suicidal purposes. The presented case concerns a fatal sodium nitrite dose purchased online. The body exhibited the characteristic blue-gray staining of hypostasis, more evident on the neck and the upper third of the posterior surface of the chest, and toxicological analysis revealed methemoglobin levels exceeding 30%. Although there is no standardized analytical procedure, the determination of nitrite in postmortem samples is crucial in these cases. Additionally, nitrite is difficult to detect postmortem because it rapidly turns into sodium nitrate. In the case presented, capillary ion analysis (CIA) with direct UV detection was performed for the qualitative and quantitative determination of nitrite and nitrate in the cadaveric central blood samples. The analytical determination identified the presence of nitrite ions and sodium nitrate, in a concentration of 9515 µmol/L.

1. Introduction

Suicide is a public health problem with a major impact worldwide, being the third leading cause of death in the 15–29 age group [1,2]. According to the latest estimates provided by the World Health Organization (WHO), suicide is responsible for more than 1 in 100 deaths (1.3%) globally, representing approximately 703,000 deaths each year. Furthermore, epidemiological data show that the age-standardized suicide rate is 2.3 times higher in men and that 58% of all suicides occur in people aged 50 years. This is a widespread and complex phenomenon, regardless of age or socioeconomic status. However, it is well known that specific conditions increase the risk of suicidal thoughts and suicide. These include pre-existing psychiatric disorders (especially mood disorders), social factors such as isolation and violence, along with pathological conditions such as cancer and neurological disorders [3,4,5]; epilepsy, Huntington’s disease, head injury, and cerebrovascular accidents especially carry an elevated risk of suicide [6].

Over time, many theories have been developed to explain the relationship between suicidal thoughts, suicidal behavior, and suicide. It has been emphasized that suicidal ideation is much more prevalent than suicide itself, highlighting that other factors determine the transition from ideation to attempted suicide. One proposed theory in 2015 has gained popularity among researchers. Known as the Three-Step Theory (3ST), it describes the conditions under which suicidal thoughts and suicide attempts arise, focusing on four key factors: distress, hopelessness, connection, and suicidal capability [7].

The most common methods of suicide for men aged 15–29 are hanging (42.7%), falling from a height (24.8%), jumping in front of a moving object (13.8%), firearms (8.5%), carbon monoxide poisoning (1.6%), poisoning by drugs and other substances (1.6%), stabbing (1.2%), and drowning (0.8%) [8]. However, there are global differences in the most used methods of suicide, which are also influenced by the accessibility of weapons or substances. The use of substances of abuse for suicidal purposes has become increasingly prevalent in modern society. Dedicated marketplaces, suicide support websites, and chat rooms have sprung up on the Web, providing users with instructions on how to use and/or guidance on how to make their own suicide kits or where to find suicide kits [9,10].

Sodium nitrite (NaNO₂) is one of the exogenous substances used for suicide that is readily available and affordable online. It is specifically included in some kits made for this purpose on dedicated channels on the Internet. The kit is usually composed of sodium nitrite, antiemetics such as metoclopramide, and antiacids such as ranitidine or cimetidine and is sold with instructions on how to take it and the dose to use to reduce its side effects and increase its gastrointestinal absorption to maximize its toxic or lethal effects [9,11,12].

This salt is a very common compound used in the acute treatment of cyanide intoxication, but also as a meat additive (known as E250) to reduce the growth of contaminating bacteria such as Clostridium botulinum or to improve meat smell and taste due to its ability to bind to the myoglobin present in meat [13]. Because of this use, sodium nitrite poisoning can also occur accidentally [14] by consuming foods above the threshold dose, which is set at 80 mg/kg for meat products [15].

We present a new case of suicide related to the use of sodium nitrite that was analyzed at our Institute of Forensic Medicine. We also carried out a review of the literature to highlight the elements that characterize this suicide case, which seems to represent a new worrying and increasing trend, and to focus on the most important data from a forensic and toxicological perspective.

2. Case Description

2.1. Circumstantial Data

The corpse of a 31-year-old man was found lying supine on the floor of his bedroom with a 500 g packet of sodium nitrate nearby. According to family members, the man suffered from depression for which he was taking medication. He had previously attempted suicide three times by ingesting toxic substances (bleach) and abusing drugs bought online.

2.2. Autopsy Findings

On external examination of the cadaver, the hypostases were located at the back and rising to the upper third of the thorax with the typical “cloak” arrangement (Figure 1A–C). The color of the hypostases varied from purplish on the back to bluish-gray more evident on the neck and on the upper third of the posterior chest. Subungual cyanosis was also present on both hands.

Autopsy revealed numerous intrascissural subpleural petechiae in the lungs, the cut surface of which was purplish red, intensely congested, and edematous, discharging fluid blood mixed with foam when squeezed. There were also signs of non-specific congestion in the brain, heart, liver, kidneys, and spleen.

2.3. Toxicological Investigations

Toxicological analyses were carried out on biological samples collected during the autopsy (peripheral blood, vitreous humor, urine, and central blood). In order to ensure the high stability of postmortem MetHb, blood samples were collected and stored at +4 °C in EDTA tubes until analysis [16]. This refrigerated storage condition was maintained for approximately 48 h prior to testing.

Urine was screened for common drugs of abuse (opioids, benzodiazepines, cannabinoids, cocaine, and amphetamines) on an ILab Taurus^® system (Instrumentation Laboratory SpA, Milan, Italy) using CEDIA DoA (Drugs of Abuse) reagents (Instrumentation Laboratory SpA, Milan, Italy). The qualitative analyses were positive for benzodiazepines and negative for the other classes of substances. Qualitative toxicological investigations into the blood samples yielded negative results.

A systematic toxicological analysis (STA) for the detection of both pharmaceutical medications and non-volatile drugs of abuse was performed by gas chromatography coupled with mass spectrometry (GC-MS) (Agilent Technologies, Palo Alto, CA, USA) in full-scan mode in the urine and central blood. The analyses revealed in both matrices the presence of citalopram, an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class used for the treatment of major depressive disorder, obsessive compulsive disorder, panic disorder, and social phobia.

The qualitative and quantitative analyses performed in the urine and peripheral blood for the detection of compounds belonging to the class of benzodiazepines by GC-MS in selected ion monitoring (SIM) mode revealed the presence of 7-aminoclonazepam (major active metabolite of clonazepam, a medication used for the acute treatment of panic disorder, epilepsy, and nonconvulsive status epilepticus), with a concentration of 195 ng/mL and 75 ng/mL, respectively.

Citalopram qualitative and quantitative analyses on the urine and central blood samples were carried out using GC-MS in SIM mode, with values of 514 ng/mL and 109 ng/mL, respectively.

Analysis of ethyl alcohol and volatile organic substances was performed by headspace gas chromatography with flame ionization detection (HS-GC-FID) on both the urine and central blood samples, pointing out negative results.

Chemical analyses were performed to detect nitrites, nitrates, and methemoglobin (MetHb) in the central blood sample. Unfortunately, obtaining a reliable assessment of nitrite or nitrate levels in the blood is challenging. The direct quantification of nitrite (NO2⁻) and its oxidized form, nitrate (NO3⁻), in biological samples is rarely conducted, resulting in the probability of false-negative results. Sodium nitrite results in the increase in the concentration of MetHb, which normally constitutes only 1–2% of the total circulating hemoglobin. Determination of the methemoglobin percentage, as an indirect search for nitrite and nitrate and a reliable indicator of the toxic effect of sodium nitrite, was performed using a blood gas testing system. The analysis resulted in the determination of MetHb, with a methemoglobin level of >30%. To perform this analysis, the GEM^® Premier™ analyzer (Instrumentation Laboratory SpA, Milan, Italy) was employed, which has an upper detection limit of 30%. Consequently, it was not possible to accurately quantify the %MetHb in the sample, which may have exceeded this threshold.

Capillary ion analysis (CIA) with direct UV detection was performed for the qualitative and quantitative determination of nitrite and nitrate in the cadaveric central blood sample. Although nitrite is the primary toxic agent responsible for methemoglobinemia and nitrates are less toxic metabolites, under certain conditions, nitrates can be reduced to nitrites in the body, and this conversion may contribute to the development of methemoglobinemia [17,18,19]. For this reason, a combined measurement of both nitrite and nitrate was performed.

The analytical determination identified the presence of nitrite ions and sodium nitrate, with a concentration of 9515 µmol/L. The results are summarized in

Table 1. Results obtained by the different techniques in central and peripheral blood and urine samples. In the last columns, therapeutic and toxic ranges in blood are reported [20].

	Central Blood	Urine	Peripheral Blood	Therapeutic Range (mg/L)	Toxic Range (mg/L)
7-aminoclonazepam (ng/mL)	n.p.	195	75	n.a.	n.a.
Citalopram (mg/L)	0.514	0.109	n.p.	0.05–0.11	0.22–2.45
Et-OH (g/L)	n.d.	n.d	n.d.	n.a	1000–2000
% Methemoglobin	>30%	n.p.	n.p.	n.a	25–30%
Nitrites (NO2−), nitrates (NO3−) (µmol/L)	9515	n.p.	n.p.	0.1–10 [21]	n.a.

Legend: n.p.: not performed; n.d.: not detected. n.a: not applicable.

.

The cause of death was therefore attributed to methemoglobinemia due to acute intoxication with sodium nitrite.

3. Literature Review

3.1. Search Strategy

The literature review was conducted by searching on the Scopus, PubMed, and Web of Science databases with the following search terms: ‘MetHb, forensic toxicology, sodium nitrite, suicide’. No filters have been set for the publication language or year of publication. Inclusion criteria were articles that presented cases of forensic interest related to the ingestion of sodium nitrite. Only free full texts or manuscripts accessible through our university database were included in the review.

No time filters were applied. A total of 52 studies were identified, of which 30 were excluded for the following reasons: duplicate articles (11), abstract only (4), review and/or commentary (6), and irrelevant to the research topic (9). Therefore, 22 studies with a total of 103 cases were included in the present review. Data from included studies were tabulated in Microsoft Excel sheets, which allowed classification according to the year of publication, author, sex, age, methemoglobin level, sodium nitrite concentration, sodium nitrate concentration and analytical methodology, and external and internal signs at autopsy, as shown in

Table 2. Cases of sodium nitrite fatalities described in the forensic literature.

Author	Year	Cases/Sex	Age	Autopsy Findings	Toxicology (Nitrite/Nitrate)	MetHb Range	Type of Event
Durao et al. [9]	2020	1 M	37	External examination: Intense scleral congestion and cyanosis of the extremities, brown-gray-blue-red hypostasis. Autopsy: Tardieu petechiae and intense polyvisceral congestion; chocolate brown color of the blood, pulmonary edema, and coronary artery disease.	Sample: femoral blood and gastric content; methodology: spectrophotometry	N.A.	Suicide
Dean et al. [10]	2020	2 M, 1 F	22–39	External examination: gray hypostasis; autopsy: brown color of blood.	N.A.	62%; 33%; 44%	Suicide
Szoradova et al. [11]	2024	2 M, 2 F	19–33	External examination: grey-purple-brown-blue discoloration of the skin. Autopsy: dark brown color of the blood; swelling of the brain and lungs, blood effusions under the pleura, and dark red-gray-brown coloring of the organs.	Sample: only blood in one case, with also urine, liver, kidneys, spleen, brain, lungs, stomach content in the other two cases, and also with vitreous humor in the last case; methodology: isotachophoresis with a conductivity detector (1 case)	20.24–71.4%; >70%	Suicide
Zerbo et al. [12]	2023	1 F	20	External examination: Labial and subungual cyanosis, grayish-purple hypostasis, dried brownish-green liquid around nasal and oral orifices. Autopsy: subpleural petechiae, brownish fluid in the pleural cavities, congested and edematous lungs and diffuse visceral congestion, edema and hemorrhagic petechiae of the laryngeal, the glottis, and tracheal submucosa and green-brownish foamy liquid in the tracheal lumen.	N.A.	12.8%	Suicide
Cvetkovic et al. [14]	2018	1 M	70	External examination: dark bluish red hypostasis with vibices.	Sample: blood, gastric content, liver, and kidney mixture	9.87%	Accidental ingestion
Kim et al. [18]	2022	8 M, 2 F	21–35	N.A.	Sample: peripheral blood and gastric content; methodology: ion chromatography	N.A.	9 suicide; 1 suspected adverse effect of vaccine
Andelhofs et al. [19]	2023	1 F	18	External examination: Gray-brownish hypostasis, lips and fingernails cyanosis. Autopsy: pulmonary edema with brownish foam in the airways, mild cerebral edema, and congestions of the visceral organs, “chocolate” brown blood.	Sample: liquid stomach contents and serum isolated from peripheral blood; methodology: nitrite sticks and spectrophotometry	35%	Suicide
Lee C. et al. [22]	2017	1 M, 4 F	58–76	N.A.	Sample: arterial and peripheral blood, urine, and gastric content	0.1–5.7%	Accidental ingestion
Hickey et al. [23]	2021	21 M, 7 F	20–86	External examination: grayish-brown, purple-brown, red-purple-brown, dark purple/blue, purple-gray, dusky gray, gray blue, purple-gray, gray, gray-green-blue, ash-colored hypostasis. Autopsy: brown blood.	N.A.	6–92%	20 suicides; 1 drug causing MetHb; 1 complication of alcoholism; 4 undetermined; 2 unascertained
Sedhai et al. [24]	2021	1 M	37	N.A.	Arterial blood	>10%	Suicide attempt
Stephenson et al. [25]	2022	8 M, 2 F	22–74	External examination: Blue-gray hypostasis. Autopsy: brown color of blood, pulmonary edema.	Sample: urine, vitreous humor and gastric content; methodology: urine dipstick	87.5% (1 case)	Suicide
Hikin et al. [26]	2023	12 M, 8 F	14–49	External examination: gray hypostasis.	Sample: blood; methodology: ozone-based chemiluminescence	>70% (1 case)	19 suicides, 1 not defined
Bugelli et al. [27]	2022	3 M, 1 F	27–51	External examination: Grayish-purple-blue hypostasis, subungual cyanosis. Autopsy: pulmonary edema, diffuse visceral congestion, brownish blood, acute emphysema, brain edema, and a recent microscopic subarachnoid hemorrhage focus, stretch cardiac myofibers with fragmentation.	Sample: peripheral blood and urine; methodology: high-performance liquid chromatography and ion chromatography	>30%	Suicide
Taus et al. [28]	2021	2 M	28–33	External examination: Cyanosis of hands, lips, and fingernail beds, brown-red-gray hypostasis. Autopsy: multi-organ congestion, cerebral and pulmonary edema.	Sample: blood; methodology: capillary electrophoresis	N.A.	Suicide
Hwang et al. [29]	2021	1 M	28	External examination: Reddish-purple hypostasis; dark brown face; cyanotic nails; bright red oral mucosa. Autopsy: congestion of the internal organs and pulmonary edema.	Sample: peripheral blood and cardiac blood; pericardial and cerebrospinal fluid; methodology: ion chromatography	33% (PM inspection) 26% (autopsy)	Suicide
Desrosiers et al. [30]	2023	2 M, 2 F	20–45	External examination: Brown discoloration of the skin, purple-gray discoloration of the lips.	N.A.	17.4–89%	Suicide
Andrè et al. [31]	2022	1 F	31	External examination: cyanosis of the extremities.	Sample: aqueous solution made from the unknown white powder; methodology: ion chromatography	20.5%	Suicide
Tomsia et al. [32]	2021	1 M	23	Eternal examination: Dark purple discoloration of the upper and lower lips, cyanosis of the fingers. Autopsy: Gray-yellowish-brown mucous membrane of the trachea.	Sample: femoral blood, urine, vitreous humor, gastric contents, liver, kidney, and costal cartilage; methodology: Griess method and spectrophotometry	N.A.	Suicide
Mun et al. [33]	2022	1 M	20	N.A.	N.A.	90.3%	Suicide
Wettestein et al. [34]	2022	1 M	25	External examination: blue-gray hypostasis.	N.A.	N.A.	Suicide
Fei et al. [35]	2024	1F (newborn)		N.A.	N.A.	3.3%	Accidental ingestion

N.A.: not applicable.

.

3.2. Review Results

The literature review showed that of the 22 studies selected [9,10,11,12,14,18,19,22,23,24,25,26,27,28,29,30,31,32,33,34,35], 20 were from the post-COVID era. The data analyzed showed that 67% out of the 103 cases involved males. The victims were aged 14 to 86 years, and 59% were under the age of 30, which is the age group with the highest number of Internet users. The cause of death was suicide in almost all cases, while accidental ingestion of sodium nitrite was in only seven cases [14,22], one of which was for placental passage in a premature newborn [35] complication of alcoholism in one case, undetermined in four cases, and uncertain in two cases [24]. In five cases, the administration of methylene blue, the specific antidote, was timely and effective.

In the population examined, 30 cases had a positive history of one or more psychiatric disorders (3 anxiety–depression, 1 panic attack, 12 depression, 3 bipolar disorder, 1 schizo-affective disorder, 2 eating disorders, 7 suicidal ideation, 2 self-harm, 5 drug overdose, 1 delusional disorder) and 12 had previously attempted suicide [9,10,11,19,25,26]. External examination of the corpse was reported in 59 cases [9,10,11,12,14,19,23,26,27,28,29,30,31,32,34], of which the appearance of hypostases was described as varying in color from dark bluish-red to mottled purple gray to gunmetal gray in 50 cases and as indeterminable due to advanced decomposition or darker skin color in the other cases. In 44 cases, external lividity was not described. In relation to postmortem laboratory investigations, a highly variable peripheral blood methemoglobin value was found, ranging from 6% to 92% [23]. This value was recorded in 47 cases, 9 of which did not report the value as an absolute number, but as being higher than the reference cut-off of the instrument employed. The sodium nitrate and nitrite values recorded showed a very wide range from 35.5 mg/L to 460 mg/L and this value was not mentioned in many cases. A wide variability also emerged in relation to the type of sample used (peripheral or central blood, urine, gastric contents, vitreous humor, cerebrospinal fluid, liver, kidney, spleen, lung, brain, costal cartilage, aqueous solution created with powder found at the scene) and the method used for analysis (deep-stick urine, spectrophotometry, ionic and liquid chromatography, Griess reaction, capillary electrophoresis, ozone chemiluminescence, isotachophoresis with conductivity detector). The most remarkable finding was the discovery of circumstantial elements near the body or in the room where the body was found. Their presence was mentioned in 81% of the case reports.

3.3. Limitations and Risk of Bias

The purpose of the literature review was twofold: firstly, to provide a summary of the aspects of forensic interest that most characterize cases of sodium nitrite poisoning; and secondly, to offer a comprehensive overview of the relevant research area. The search was conducted using keywords without the use of Boolean operators or specific filters. This, in conjunction with the decision to include solely case reports or case series, may have influenced the estimation of the results. Furthermore, it should be noted that the data of forensic interest were reported inconsistently by the researchers.

4. Discussion

Sodium nitrite is an inorganic compound that appears in the form of crystals at ambient temperature, slightly yellowish in color, odorless, and naturally soluble in water. These characteristics make it the perfect compound to be dissolved in water and consumed orally. Its toxicity is related to its ability to bind hemoglobin, the oxygen transport metalloprotein. Sodium nitrite oxidizes the bivalent iron in it to the ferrous state (Fe+3). This converts hemoglobin to methemoglobin (MetHb), shifting its dissociation curve to the left, resulting in a decreased capacity to bind and release oxygen to tissues. In the same reaction, nitrite is reduced to nitric oxide (NO), which has a strong vasodilator effect, resulting in severe hypotension, further reducing oxygen delivery to tissues and exacerbating MetHb toxicity [36]. A state of tissue hypoxia is thus created, which, if not adequately and promptly treated with its specific antidote, methylene blue, may result in the subject dying from chemical asphyxia. Usually, the amount of methemoglobin in circulating erythrocytes does not exceed 1–2%, as it is regularly reduced to hemoglobin during production by the action of NADH-dependent cytochrome b5 reductase. Methemoglobinemia is clinically evident when the concentration exceeds 10–15%, with a progressive increase in hypoxia-related symptoms. Symptoms range from headache, nausea, and fatigue to chest pain and difficulty breathing and at concentrations > 50%, more severe signs appear including tachypnea, metabolic acidosis, dysrhythmias, seizure, delirium, and coma [37]. Some authors have hypothesized that the toxicity resulting from sodium nitrite intake may also be related to direct cytotoxicity mechanisms. Nevertheless, experimental studies conducted in vitro using cellular models have failed to identify a specific mechanism, confirming that methemoglobinemia is the primary mechanism of toxicity in nitrite poisonings [38].

Although the administration of sodium nitrite for suicidal purposes has been reported in the literature, our research showed that most of the studies are relatively recent. This may suggest a new trend associated with an increase in the prevalence of this suicidal practice, also pointed out by other authors [39].

The epidemiological data confirmed the trend identified by the Global Heart study from an international perspective, i.e., the majority of victims were males (67%) and 56% of the cases involved people aged under 30, which is also consistent with the hypothesis that nitric oxide for suicidal purposes is a substance that is advertised and purchased through dedicated channels on the online market, and is therefore easily accessible to the younger population who use the Internet more easily. The frequent occurrence of a history of psychiatric disorders and/or previous suicide attempts is confirmed as a relevant risk factor for suicide in general [40,41].

As far as diagnosis is concerned, the presence of blue-gray or brownish hypostases is a strong indication of methemoglobinemia, which, if detected, should alert to specific toxicological tests.

The determination of methemoglobinemia and sodium nitrite and nitrate are not investigations that are routinely carried out in forensic toxicology labs, so it is necessary for the pathologist to carefully evaluate the presence of particular characteristics in order to properly direct the postmortem investigations, as shown in the case we presented, in which the presence of a package of salt at the death scene, together with the observation of an unusual coloration of the hypostases (blue-gray more evident on the upper third of the back and on the neck), led the pathologist to request specific analytical tests.

Although it is therefore necessary to perform toxicological investigations to determine MetHb, the analysis carried out showed that it is difficult to establish a threshold above which concentrations are certainly fatal. Some authors have pointed out that a falsely elevated methemoglobin value may be due to repeated freeze–thaw cycles of the sample or the non-use of preservatives in the sample vial; conversely, falsely reduced values may be due to postmortem hemolysis associated with microbial activity as well as the residual tissue action of methemoglobin reductase [16,42]. It should also be noted that very often, as in the case presented, the MetHb concentration was not reported as an absolute value but as greater than the cut-off of the instrument employed, thus revealing a potential bias due to the instrument used for the analysis.

Another aspect that emerges not only from the case presented, but also from the literature review, relates to the postmortem detection of sodium nitrite. The determination of sodium nitrite in blood is complex due to its very short plasma half-life (180 s); indeed, once in circulation, nitrite is very rapidly converted into sodium nitrate. The extremely brief half-life of nitrite, the substance that is responsible for toxicity, frequently complicates its identification in postmortem samples. For this reason, nitrate measurement can be used as an indirect indicator of nitrite intake in suspicious circumstances, as in the case presented.

Furthermore, in the case of nitrite, the literature review revealed a wide variability in the detected concentrations considered to be lethal. This variability may be due to the lack of a standardized analytical approach for detecting these substances, both in terms of the samples to be used and the most reliable methodology.

In this regard, the literature review revealed that in most studies, the matrix commonly used was blood (mainly femoral), followed by urine and gastric contents. Some authors reported using more unusual matrices for analysis, such as liver and kidney [11,14,32] cerebrospinal fluid and pericardial fluid [29] and even rib cartilage in one study [32].

This wide variability highlights that there is still no analytical procedure that prevails over the others. Similar considerations can be made for the analytical methods used in the different studies to determine nitrite and nitrate concentrations. Most authors used spectrophotometry and chromatography, while in some cases, simpler methods based on urine dipstick detection were used.

The information on the circumstantial findings, which were present in 81% of the cases, was crucial in directing the investigation. These included glasses with white powder residue on the bottom, a bag or container containing sodium nitrite, usually explicitly stated on the label, and instructions on how to dilute and take the compound, also in combination with antiemetics and antacids, sometimes also found at the scene. Moreover, there were suicide notes and the presence in the browsing history of the smartphones, PCs, or tablets used by the deceased of websites and chat rooms supporting suicide. Considering the points highlighted, it seems almost pleonastic to reiterate the importance of the elements found during the inspection, appropriately emphasized by the description and detailed documentation of the scene, for example, with careful photographic records, the identification of notes or telephone calls to the emergency services, or the discovery of boxes containing a white substance, sometimes labeled as sodium nitrite.

5. Conclusions

The case presented and the analysis of the literature illustrate how the use of sodium nitrite for suicidal purposes has gained some prominence in recent years. In the case analyzed, the macroscopic findings, primarily represented by postmortem lividity staining and signs of asphyxia, such as subpleural petechiae, in conjunction with circumstantial data, guided the direction of toxicological analyses. These analyses were directed towards the measurement of methemoglobinemia and the detection of sodium nitrite in the blood. The comprehensive evaluation of all pertinent factors, in conjunction with the exclusion of alternative potential etiologies, facilitated the delineation of the final diagnosis as asphyxia syndrome, secondary to methemoglobinemia arising from sodium nitrite intake.

It should be emphasized that in forensic investigations, nitrite determination is not part of routine testing, so an integrated approach is essential to avoid postmortem misdiagnosis in suspected cases. The presence of the hypostases characteristic of methemoglobinemia is an inconstant finding, and it is therefore necessary to carry out a careful analysis of the circumstantial data and those found during the investigation such as the presence of packages of drugs or substances, anamnestic investigation of psychiatric pathologies or previous suicide attempts, and investigation of computer tools used by the deceased to evaluate possible online searches, which guide the autopsy and toxicological investigations.