Toxicology and Forensic Pathology: More Than a Numbers Game

I was recently reviewing new toxicology reports from my pending autopsies, and came across a report with the following results: 

Looking at this in isolation, it would be easy to assume this person died from an overdose. Even low levels of fentanyl can be dangerous to an opioid-naive individual – a level this high is rare. Then there’s the added presence of fluoro fentanyl, a fentanyl analog, which would seem to support the notion of an overdose. The problem with this assumption? This person died from blunt force trauma as a pedestrian struck by a car. He was, according to witness accounts, walking and talking right until the moment of impact. Autopsy had shown multiple blunt force injuries incompatible with life.

This situation illustrates some of the complexity of postmortem forensic toxicology. Despite methodology being nearly the same, toxicology in a forensic setting differs in many important ways from that performed in a clinical setting.

The first major difference occurs in the pre-analytical phase. The results of clinical testing may be used to alter therapy or make a diagnosis. However, forensic toxicology results are meant to be used in a court of law, meaning the chain of custody needs to be maintained. If there is no documentation of who touched the sample and when, the integrity of the specimen can be called into question and results may be impermissible.

Not all forensic toxicology is performed on deceased patients. Specimens may be taken from the living during evaluation of an alleged assault, driving under the influence, or for workplace monitoring. In autopsy specimens though, postmortem redistribution (PMR) is another pre-analytical factor to consider. After death the stomach, intestines, and liver can serve as a drug reservoir and passively transfer the drug to surrounding vasculature. Other organs can also act as reservoirs, depending on where the drug is concentrated in life. Drugs which are highly lipid-soluble and/or have a high volume of distribution will diffuse down their gradient from adipose tissue into the bloodstream – antidepressants are notorious for this, and elevated postmortem levels need to be interpreted with caution.

Autopsy specimens are also more varied in type and quality than typical clinical specimens. Vitreous fluid, bile, and liver tissue are commonly collected at autopsy, in addition to central (heart) and peripheral (femoral or subclavian) blood. Femoral blood vessels, being relatively isolated from PMR-causing drug reservoirs, are a preferred source of specimens. Decomposition or trauma can limit the types or quantity of specimens and may even alter results. After death, bacteria from the GI tract proliferate and can produce measurable levels of ethanol in the blood. Decomposition also produces beta-phenethylamine, which can trigger a ‘positive’ result for methamphetamine on ELISA-based tests.

The post-analytical phase of autopsy toxicology also poses unique challenges. Lawyers and law enforcement will sometimes ask what the ‘lethal level’ of a drug is, and they’re invariably disappointed by my response. While there are published ranges of toxicity and lethality for most drugs, these are only general guidelines. There is no absolute lethal blood level for prescription or illicit drugs. Opioid users develop tolerance, making them relatively immune to a dose which would kill an opioid-naive person. In the example of the pedestrian described above, he had a long history of heroin abuse and could therefore tolerate much higher levels than most. For stimulants like cocaine and methamphetamine, there are no documented ‘safe’ levels as any amount could act as an arrhythmic agent. To add to the complexity, most overdose deaths involve multiple substances which may have synergistic effects and interactions that are difficult to parse.

Because of the reasons given above, the National Association of Medical Examiners still recommends full autopsy for possible overdoses. Deciding if a death was due to overdose is more complex than just reading a toxicology report – it requires interpretation and correlation with the autopsy findings and overall investigation.   


D’Anna T, et al. The chain of custody in the era of modern forensics: from the classic procedures for gathering evidence for the new challenges related to digital data. Healthcare. 2023 Mar;11(5):634.

Davis GG, et al. National Association of Medical Examiners Position Paper: Recommendations for the Investigation, Diagnosis, and Certification of Deaths Related to Opioid Drugs. Acad Forensic Pathol 2013 3(1):77-81.

Pelissier-Alicot AL, et al. Mechanisms underlying postmortem redistribution of drugs: A review. J Anal Toxicol. 2003 Nov-Dec;27(8):533-44.

Thoracic Aortic Disease at Autopsy: An Opportunity for Intervention

When I perform an autopsy, I know that anything I find will be discovered too late to save my patient’s life. I generally hope the autopsy report helps explain why and how someone died to family members, law enforcement, lawyers, and potential jurors.  It’s less common that an autopsy finding can have immediate impact on the healthcare of the decedent’s family, but this is the case with thoracic aortic disease.

Thoracic aortic aneurysms and/or dissections (TAAD) are relatively common mechanisms of sudden, unexpected, and natural death we encounter in forensic pathology. The classic teaching is that TAAD are caused by hypertension, bicuspid aortic valves, pregnancy, and cocaine use. Genetic disease1,2,3 is included late in the list, almost as an afterthought, with Marfan syndrome given as the prototype. However, the evidence for a genetic underpinning of TAAD has been steadily expanding. Family pedigrees in the late 1990s revealed up to 20% of patients with TAAD had an affected first-degree relative.4,5 If extended to 2nd degree relatives, up to 43% of patients with TAAD had at least one affected family member.6 There are also now more than 15 types of defined connective tissue diseases, and more than 29 genes identified which are mutated in heritable TAAD (H-TAAD). Clearly, the etiologies of hereditary TAAD (H-TAAD) expand far beyond Marfan syndrome.

H-TAAD can be categorized as “syndromic” or “non-syndromic” and has wide variability in clinical presentation. Syndromic forms show multisystem involvement, and often have externally apparent phenotypes. The most common forms of syndromic H-TAAD are Marfan syndrome, vascular Ehlers-Danlos, and Loeys-Dietz syndrome. However, the physical appearances associated with these syndromes can be subtle and aren’t always present.7 Non-syndromic H-TAAD affects only the aorta and aortic valve and includes both bicuspid aortic valve-associated TAAD and “familial” H-TAAD.

Thoracic aortic disease often remains subclinical until serious, life-threatening complications occur. Forensic pathologists can therefore play an important role in preventative health, proactively identifying patients at high risk for TAAD. Because a relatively large percentage of thoracic aortic disease is hereditary, it is prudent to ask whether forensic pathologists should initiate genetic testing in these situations.  Unfortunately, postmortem genetic testing is still out of reach for most Medical Examiner and Coroner systems. Insurance companies don’t reimburse for postmortem genetic tests, even when requested by healthcare providers of the surviving family. Selective testing of decedents with high-risk features may be more affordable, but there is no consensus on what those “high-risk” features are – and because of the variable penetrance and expressivity of H-TAAD, patients can present at nearly any age (even in their 80s).5,6

Despite the limitations of access to postmortem genetic testing, the most practical resource forensic pathologists have at our disposal is the telephone. According to 2022 guidelines from the American College of Cardiology and American Heart Association, aortic imaging is recommended in all first-degree relatives of patients with TAAD to screen for occult disease.8 Family members therefore need to be notified of this recommendation, regardless of the pathologist’s choice to pursue genetic testing. Developing a collaborative relationship with a local hospital or academic center may be beneficial; medical examiner offices then have a place to refer families for screening, and genetic counselors in these locations are better suited to evaluate the entire family and potentially order targeted genetic tests.9

Forensic pathologists are in a crucial position to recognize potential H-TAAD. Surgical outcomes for patients with TAAD are much better when performed prophylactically rather than emergently, so identifying aortic disease prior to rupture or dissection is crucial. Premature attribution to hypertension, or overreliance on the presence of Marfan-like features to identify hereditary disease, will result in missed opportunities to save lives. Forensic pathologists can therefore have a significant impact on public health, by recognizing the heritability of TAAD and contributing to improved screening of families at risk.


  1. Prahlow JA, Barnard JJ, Milewicz DM. Familial thoracic aortic aneurysms and dissections. J Forensic Sci. 1998 Nov;43(6):1244-1249.
  2. Gleason T. Heritable disorders predisposing to aortic dissection. Semin Thorac Cardiovasc Surg. 2005 17:274-281.
  3. Gago-Diaz M, Ramos-Luis E, Zoppis S. Postmortem genetic testing should be recommended in sudden cardiac death cases due to thoracic aortic dissection. Int J Legal Med. 2017 Sep;131(5):1211-1219.
  4. Biddinger A, Rocklin M, Coselli J, et al. Familial thoracic aortic dilatations and dissections: a case control study. J Vasc Surg. 1997;69:506-511.
  5. Coady MA, Davies RR, Roberts M, et al. Familial patterns of thoracic aortic aneurysms. Arch Surg. 1999;134:361-367.
  6. Chou AS, Ma WG, Mok SCM, et al. Do familial aortic dissections tend to occur at the same age? Ann Thorac Surg. 2017 Feb;103(2):546-550.
  7. Isselbacher EM, Cardenas CLL, Lindsay ME. Hereditary influence in thoracic aortic aneurysm and dissection. 2016. Circulation 133(24):2516-2528.
  8. Isselbacher EM, Preventza O, Hamilton Black 3rd J, et al. 2022 ACC/AHA Guideline for the diagnosis and management of aortic disease: A report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines. Circulation. 2022 Nov 2. Online ahead of print.
  9. Krywanczyk A, Rodriguez ER, Tan CD, Gilson T. Thoracic aortic aneurysm and dissection: Review and recommendations for evaluation. Am J Forensic Med Pathol. 2023 Mar 6.

-Alison Krywanczyk, MD, FASCP, is currently a Deputy Medical Examiner at the Cuyahoga County Medical Examiner’s Office.

The Importance of Patient Identification in Forensics

Body identification is one of the core responsibilities of a forensic pathologist yet is also probably the most common one to be overlooked. Most of the deceased people who come to our office are visually identifiable, and the identity may already have been confirmed if they were transported to the hospital. In some situations, though, the body may be disfigured by fire, decomposition, injury, or there may only be partial remains recovered. In incidents with multiple fatalities, we need to be sure the correct remains are returned to the correct family. Particularly when foul play is involved, there may be intentional attempts to conceal the decedent’s identity or disguise them as another person.

There are two different levels of identification: “positive” identification (the gold standard) and “presumptive” identification.

The three generally accepted forms of “positive” identification are DNA comparison, fingerprint comparison, and radiograph comparison. While television shows have DNA “matches” coming back in the time it takes for a commercial break, DNA identification can pose challenges. A pre-existing specimen from the decedent or close family members is needed for comparison, which means you need to already have some suspicion of who they are. If they’ve been previously arrested or charged with a felony (the laws vary slightly by state), their DNA may have been uploaded to the Combined DNA Index System (CODIS), and a match may potentially be obtained blindly by uploading the decedent’s sample. By comparison, one can collect fingerprints from a decedent and submit them to the Automated Fingerprint Identification System (AFIS) for relatively rapid identification. Many people have been fingerprinted in their lifetime, whether for relatively minor arrests, employment, or background checks. However, there are still limitations. The hands (or at least fingertips) need to be intact, with printable skin. For mummified remains, the tissue can be rehydrated by soaking in sodium carbonate or sodium hydroxide to obtain legible prints. “Degloved” remains, where the skin has sloughed from the hands due to decomposition, can be fingerprinted by inserting one’s gloved hand into the sloughed skin.

Radiographs, like DNA, are limited by the need to have a pre-existing sample from the decedent (meaning you need to know who they might be). Radiographs are invaluable when trying to identify someone with no usable fingerprints, or no fingerprints on file. A variety of locations can be used for comparison, including the dentition, frontal sinuses, vertebral processes, healed fractures, or orthopedic implants. Serial numbers on implanted devices can also be traced back to the decedent, although not all implantable devices have such markings.

“Presumptive” identifications are based on many other common sense factors including context, visual identification, tattoos, belongings, and clothing. Depending on the context of the case, a presumptive identification may suffice. For a decomposed body in a secure apartment occupied by a single, elderly person the neighbors haven’t seen in days, monogrammed dentures within the mouth may be sufficient. But in a fire with three charred female victims, aged 20-25, it’s much more important to confirm the identifications by a positive method. As I mentioned earlier any situation involving foul play may provide motivation for to conceal a victim’s identity, and so all homicide victims must be positively identified. It’s often taken for granted that the tag on our patient’s toe is accurate, but we need to approach our autopsies with the same level of diligence a laboratorian has when evaluating the label on a blood tube. Knowing who your patient is, and who your sample comes from, is the first critical step for any pathologist.

The mummified remains of a young adult were found in an abandoned house; while the fingertips were initially too dessicated to yield fingerprints, rehydration revealed excellent ridge details. Fingerprints were then uploaded to AFIS, and the decedent was identified within an hour.
For skeletal remains with intact teeth, dental radiographs of the remains can be used for identification; however, for edentulous patients, a different strategy must be used.

-Alison Krywanczyk, MD, FASCP, is currently a Deputy Medical Examiner at the Cuyahoga County Medical Examiner’s Office.

The Basics of Deaths by Fire: Answering Your Burning Questions

Emergency services were called to a fire in a small apartment building, in which the structure was completely engulfed. Most of the occupants had been evacuated – however, once the fire was extinguished, the charred remains of an adult woman were found in the debris.

At the autopsy of severely fire-damaged human remains, two key questions must be answered: 1) who is the decedent?, and 2) were they alive when the fire started?

Question #1 is particularly relevant in this case, as many people lived in the building. Presumptive identification based on the tenant list may seem reasonable at first, but this victim could represent a visitor, contractor, or subletter. When facial identification isn’t possible, radiographic identification can be done with dental x-rays or x-rays of other bones which may have unique features from healed trauma or degeneration. Additional methods of positive identification could include fingerprints (if still intact), or DNA comparison to first degree relatives.

Question #2 is of importance because fire can be used in an attempt to disguise the identity of a victim of violent crime and destroy evidence. Cutaneous evidence of trauma may be disguised by burns, so full body x-rays are taken of every fire-damaged body. X-rays can also reveal retained bullets, knife tips, or fractures unlikely to have been caused by the fire.

When deciding if a fire victim was alive when the fire started, we first examine the upper and lower airways for soot.  Most fire victims do not die from cutaneous burns, but from smoke inhalation – including carbon monoxide (CO) toxicity, which is often apparent by cherry red discoloration of the blood and viscera. Postmortem carboxyhemoglobin measurements in house fire victims are typically greater than 50%. There are exceptions to this rule, of course. Rarely, someone who was clearly alive when the fire began will have minimal or no soot in their airways and a negligible carbon monoxide concentration. This can happen in a “flash fire”, such as one ignited by gasoline or oxygen tanks, in which thermal injury to the upper airway may cause rapid occlusion by laryngospasm or edema. People with underlying heart or lung conditions will be more susceptible to the effects of carboxyhemoglobin, and may not survive long enough to obtain a level above 50%. Fires also produce other toxic products of combustion such as cyanide, and can lower ambient oxygen saturations to result in asphyxiation by lack of ambient oxygen (even without CO).

Forensic pathologists need to be aware of the artifacts that fires can create. Pugilistic posturing of fire victims (limb flexion) is due to heat-related contraction of muscle fibers. Epidural hematomas can result from boiling blood and bone marrow within the calvarium extravasating into the epidural space. The heat can induce fractures in exposed bone once the surrounding soft tissue is consumed or fully charred. Finally, the heat can split apart skin and soft tissue, resulting in sharp-force-like defects which occur parallel to the orientation of muscle fibers (rather than across them, which is more suspicious for penetrating trauma).

Of utmost importance in fire-related deaths, however, is scene investigation. The manner of death in fire fatalities is related to the origin of the fire. Most fire deaths are accidental, as the fire is unintentionally sparked by some electrical malfunction or unattended flame. However if the fire started intentionally, the manner of death can be homicide (if started by another) or suicide (started by the victim). It is therefore crucial to review the final fire investigation report before finalizing the autopsy report and death certificate. 

This image shows dark black soot lining the main and lobar bronchi; this indicates the victim was breathing during the fire.
Heat-related epidural hematomas have a brown, amorphous appearance rather than the bright red color of traumatic epidural hematomas.
The scalp has been consumed by fire, and the exposed bone is calcined and brittle with fractures of the outer table.

-Alison Krywanczyk, MD, FASCP, is currently a Deputy Medical Examiner at the Cuyahoga County Medical Examiner’s Office.

Determining Time of Death: Separating Science from Pseudoscience

One of the most common questions I’m asked by family members is “do you know when they died?” If death occurs in the hospital, or is witnessed, the time of death isn’t controversial. It’s common though in forensics that people may not be found for hours, days, weeks, or more. Forensics television shows usually depict an investigator measuring body temperature at the scene, and then confidently declaring they’ve been dead for 44 hours. Unfortunately, there aren’t any existing methods that actually give that level of precision – but there is a way we can systematically approach the question.

When determining time of death (TOD), it’s most important to keep in mind that it will be an estimate. The estimate starts with the “window of death” – the time between when the decedent was last known alive and when their body was found. The smaller this window, the greater accuracy is possible.

Once the window is known, one can assess postmortem changes of the body. Livor mortis is the gravity-dependent settling of blood within vessels, which can appear as soon as twenty minutes after death. Sparing of lividity will be present in areas of pressure, such as parts of the body pressed against the floor or with tight clothing. Livor is initially blanchable, but after 8 to 12 hours blood extravasates from vessels and it becomes “fixed”. Clearly though, this only allows one to differentiate between ‘less than’ or ‘greater than’ 8 to 12 hours.

Rigor mortis (stiffening of the body after death) occurs because of postmortem ATP depletion. Muscle fibers require a supply of ATP to both contract and relax – once ATP levels are sufficiently low, muscle will remain contracted until the fibers are broken down by decompositional changes. Generally speaking, rigor starts to develop within an hour of death, peaks from 12 to 24 hours, and dissipates by 36 hours. However, these are average intervals. The onset of rigor is hastened by vigorous physical activity, seizures, electrocution, or increased body temperature, which preemptively deplete ATP. Rigor is also harder to detect in people with low muscle mass (e.g. infants), and can’t be assessed in frozen bodies with those with extensive thermal damage.

Cooling of the body after death, known as algor mortis, is similarly prone to interfering elements. One can find many formulas for estimating the time of death based on the temperature of the body – unfortunately, none of them are particularly useful because of the assumptions that must be made. Change in temperature after death is affected by numerous variables, including body habitus, clothing, wind, actual body temperature at the time of death (not many people are constantly at 98.6℉), sepsis, terminal seizures, and many others. If the environment is warmer than the body, the temperature can even increase after death.

I’ll briefly mention vitreous potassium measurement, which is probably the most recently discovered (and debunked) “holy grail” of time of death. Similar to algor and rigor mortis, vitreous potassium does a reasonably decent job predicting time of death in a controlled experiment – but in this line of work, people don’t tend to die in controlled environments.

At the end of the day, time of death is best estimated by thorough scene investigation, correlated with the evidence the body provides. Newspapers or mail not retrieved from the mailbox, expiration dates on perishable groceries, last refills of prescriptions, and unreturned text messages or phone calls can all narrow down the window of death.

As stated earlier, the longer the interval between death and discovery of the body, the more difficult time of death determination becomes. In advanced decomposition, there is no rigor, livor, or algor remaining to assess (there may even be scant residual soft tissue). In one such situation, despite months of a potential “window of death”, dates on unopened bills and crossed-off calendar dates helped us place the time of death within one or two days. It’s not as flashy as multivariate equations for temperature or potassium levels, but it’s far more accurate and scientifically defensible.

Image 1. The quilting pattern of this decedent’s mattress is visible in the livor mortis on his back.
Image 2. This decedent’s right arm is defying gravity due to rigor – he was initially face down, and his arm musculature became temporarily fixed in this position. Rigor can be forcibly broken if needed, but will also break down as decomposition proceeds.

-Alison Krywanczyk, MD, FASCP, is currently a Deputy Medical Examiner at the Cuyahoga County Medical Examiner’s Office.

Dying in a Winter Wonderland: Staying Safe as the Temperature Drops

A 40 year old man was found deceased in a parking garage in a Midwest city. It was late October and had rained the previous evening. He was identified by his sister who was a tenant in the adjacent apartment building. Unknown to her, he had recently been discharged from the hospital after a one-week psychiatric admission. His sister stated he was homeless and would occasionally sleep in the parking garage for shelter.

At the scene the decedent was prone on the ground, clad only in a pair of boxers. His water-soaked shoes, socks, sweatpants, and shirt were strewn about him. Autopsy revealed an atraumatic, thin adult man. Prominent pink discoloration was noted over the hips and knees. Internal examination showed only patchy black-brown discoloration of the gastric mucosa and pale kidneys. Histology was remarkable for subnuclear vacuolization of the renal tubular epithelium. The cause of death was certified as environmental hypothermia, and the manner of death accidental.

Hypothermia is defined as a core body temperature below 95℉ (35℃) and can result from endogenous illnesses like hypothyroidism or sepsis. The most common cause, though, is exposure to cold environments. On exposure, the hypothalamus initiates shivering and increases cellular metabolism to produce heat. Another crucial survival response is vasoconstriction, particularly of vessels in skin and skeletal muscle. If the overall loss of heat overtakes the body’s ability to produce or retain heat, hypothermia will result.

Developing hypothermia doesn’t require frigid weather – in dry air, temperatures of 50℉ can still result in hypothermia. Wind removes warmed air surrounding the body, and water conducts heat three times faster than air; therefore, with either of these factors present, people can develop hypothermia at even warmer temperatures,

The autopsy findings of hypothermia are not specific. External examination may show bright pink discoloration of the skin over joints (“frost erythema”). There may be black-brown spots on the gastric mucosa, (“Wischnewsky spots”), thought to result from terminal vasodilation of submucosal vessels. The kidneys may be pale with microscopic subnuclear vacuolization of the tubular epithelium (the “Armanni-Ebstein” lesion). Acute hemorrhagic pancreatitis has also been described. However, these findings require a period of survival to develop—many cases, particularly if the decedent succumbs quickly, show no findings at all. The diagnosis of hypothermia therefore relies heavily on scene investigation. “Paradoxical undressing” (demonstrated in this case), refers to the phenomenon of a terminally hypothermic person taking off their clothes. This is caused by a feeling of warmth resulting from failure of vasoconstriction in the skin, and contributed by altered mentation.

Those at greatest risk are people spending extended time outdoors, including the homeless and outdoor recreationalists. The elderly and very young have a lower ability to centrally regulate body temperature. Children’s increased body surface area also leads to more rapid heat loss. People who are intoxicated with alcohol or drugs may not sense the cold or lack judgment to seek shelter. Alcohol also acts as a vasodilator, impairing vasoconstrictive adaptation to cold.

As the weather cools down, be mindful of how easily hypothermia can develop. Temperatures can be above freezing, yet those who are vulnerable are still at risk of hypothermia. Prepare yourself well for any snowy excursions, and keep an eye on those in your community who may not be able to seek shelter.

Stomach mucosa showing spots of black or dark brown discoloration
known as Wischnewsky spots. These are not specific to hypothermia and may just be an indicator of physiologic stress.
Bright pink discoloration over the knees, or “frost erythema”.
Pallor of the renal cortices corresponds to the microscopic “Armanni-Ebstein” lesion. This isn’t specific to hypothermia and can be seen in ketoacidosis from any cause.

-Alison Krywanczyk, MD, FASCP, is currently a Deputy Medical Examiner at the Cuyahoga County Medical Examiner’s Office.