A post-mortem toxicology report is a lab record of which substances were found in the body, such as medicines, street drugs, alcohol or poisons, and often how much of each. Finding a substance is not the same as finding the cause of death, because levels can shift after death and a dose that kills one person can be routine for another.1PubMed Central. Thinking beyond blood: brain concentrations and brain–blood ratios in postmortem toxicology The medical examiner treats the report as one piece of evidence, weighed with the autopsy, the medical history and the death scene, and not as a verdict by itself.2Academic Forensic Pathology. National Association of Medical Examiners Position Paper: Recommendations for the Investigation, Diagnosis, and Certification of Deaths Related to Opioid Drugs
What the Report Lists and How Labs Find It
Testing happens in two stages. Most labs begin with a fast screening test that reacts to broad drug groups like opioids, amphetamines, benzodiazepines and cannabis.3PubMed. Comparison between drug screening by immunoassay and ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry in post-mortem urine Positive or suspicious results are then confirmed with more precise instrument testing that identifies the exact substance and its amount.4PubMed. Efficacy of drug screening in forensic autopsy: retrospective investigation of routine toxicological findings These methods can search for hundreds of drugs and their breakdown products in a single run.5PubMed. Postmortem drug screening by non-targeted and targeted ultra-performance liquid chromatography-mass spectrometry technology The confirmation step exists because other chemicals in the body can interfere and set off a false alarm, and the screen can miss drugs present below its cutoff.6PubMed. Comparison between drug screening by immunoassay and ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry in post-mortem urine
Many reports show no drugs of abuse at all. In one large series of autopsies, about 8 in 10 screens for drugs of abuse were negative.7PubMed. Efficacy of drug screening in forensic autopsy: retrospective investigation of routine toxicological findings Even so, the follow-up testing in that series still turned up everyday medicines such as acetaminophen, aspirin, antipsychotics and low levels of sedatives.8PubMed. Efficacy of drug screening in forensic autopsy: retrospective investigation of routine toxicological findings
Each line of a typical report usually names a substance, the sample it came from, and either an amount or simply “detected.” Breakdown products often appear next to the drug itself, which shows the body had begun processing it. Amounts are given in units such as mg/L or ng/mL, which describe concentration. “None detected” means nothing was found above the lab’s limit, not that the person never took anything. If a value is unclear, the examiner can explain what it means.
A “detected” line says the substance was present in the sample. It does not say when it was taken or whether it was affecting the person at death. Some sedatives and cannabis breakdown products linger well after their effects wear off. A drug listed with plenty of breakdown products suggests the body had time to process it, while a drug with few or none can hint at more recent use, though that is one clue among several and not a dependable test. The examiner reads such clues alongside the scene and history, so a single line rarely answers “when did they take it?”
A positive screen only says something in a drug group may be present, so look for the confirmed result, which names the exact substance. If the report shows only a screen result, it is reasonable to ask the examiner’s office whether confirmation testing was done.
A standard panel targets common drugs. Rare poisons, metals or plant toxins need specific requests, and examiners order extra tests when the history or scene suggests something unusual. A family that suspects a particular substance can tell the medical examiner’s office early.
Which Samples Are Tested and Why It Matters
Reports often list vitreous humor, the clear fluid inside the eyeball, alongside blood and urine. It sits in a protected space, less affected by bacteria and decay, and stays stable longer after death.9PubMed. Vitreous humor endogenous compounds analysis for post-mortem forensic investigation For some drugs, including cocaine, heroin’s breakdown product and PCP, eye fluid can show use for longer than blood can.10PubMed Central. Vitreous humor analysis for the detection of xenobiotics in forensic toxicology: a review
Blood and urine tell different stories. Blood levels reflect what was circulating near the time of death. Urine often shows substances used hours or days earlier that may no longer be active, so a drug found only in urine may point to earlier use and not to effects at death. Comparing samples helps the examiner judge timing.
Some reports note “femoral blood,” which is blood taken from a leg vein. It is farther from the organs that leak drugs after death, a process explained below, so it is preferred. Blood from the heart can read higher and is interpreted more cautiously.
Labs also adapt when the usual samples are missing. When there is no urine in the bladder, staff can rinse it with saltwater and test the rinse instead.11PubMed. Bladder wash: a proof of concept as an alternative specimen for postmortem toxicology That rinse matched urine results more than 99% of the time and found drugs in cases that would otherwise have gone untested.12PubMed. Bladder wash: a proof of concept as an alternative specimen for postmortem toxicology
Other tissues may be tested too. Liver tissue is often sampled because it stores many drugs and can show exposure when blood is limited or unavailable. Stomach contents can help show whether pills or a drink were swallowed shortly before death, though they say little about how much was absorbed. When a body is badly decomposed, muscle or other tissues may be the only samples left.
What an Alcohol Result Really Means
Bacteria and yeast that break down the body can produce alcohol after death, making it hard to tell from drinking.13PubMed. Postmortem production of ethanol and factors that influence interpretation: a critical review In unpreserved tissue kept even in a fridge, alcohol rose more than tenfold on average within four days.14Federal Aviation Administration. The Formation of Ethanol in Postmortem Tissues A low alcohol reading in a body found after some time therefore does not by itself prove the person had been drinking.
Examiners have ways to tell. One clue is a drinking marker called EtG, which the body makes only from alcohol it has processed.15PubMed. Ethyl glucuronide and ethanol concentrations in femoral blood, urine and vitreous humor from 117 autopsy cases Alcohol in blood with no EtG anywhere and none in eye fluid points to alcohol made after death.16PubMed. Ethyl glucuronide and ethanol concentrations in femoral blood, urine and vitreous humor from 117 autopsy cases Other alcohols made by microbes can also signal that bacteria, not drinking, produced the alcohol.17PubMed Central. Modeling Postmortem Ethanol Production/Insights into the Origin of Higher Alcohols Examiners weigh case history, the condition of the sample and how alcohol is spread across samples as well.18PubMed. Postmortem production of ethanol and factors that influence interpretation: a critical review
A positive alcohol line is not automatically evidence of drunkenness. If the result surprises you, ask whether EtG or eye fluid was tested.
The circumstances of the body matter as well. Microbes grow faster in warmth, so the length of time before the body was found and the temperature around it both count. A body found quickly and kept cool gives bacteria less chance to make alcohol, so a result there is more likely to reflect drinking. Injuries that damage the gut can let microbes spread and add to after-death alcohol.
Other samples add detail. Alcohol in urine without matching alcohol in eye fluid can suggest drinking happened earlier, or that microbes were active in the bladder. Alcohol in the stomach contents can show a drink was recent, but not how much the person had absorbed. Blood, urine and eye fluid all showing similar levels makes real drinking more likely than a lone blood reading does.
Why Drug Levels Can Change After Death
After death, drugs stored in the stomach, liver, lungs and heart can leak into nearby blood.19PubMed. Mechanisms underlying postmortem redistribution of drugs: a review Because these organs sit close to large blood vessels, this leaking is thought to be the main source of change.20PubMed Central. Postmortem redistribution of drugs: a literature review Blood also settles with gravity, changing levels at different spots in the body.21PubMed Central. Postmortem redistribution of drugs: a literature review A blood level measured after death can therefore read higher than what the person had while alive.
Examiners may take blood from more than one site and compare. A big gap between two sites suggests drugs shifted inside the body after death, so the higher number is treated with caution. This is why the report names where each sample came from.
Drugs differ in how much they shift. Those that concentrate in organs such as the lungs and liver move more than drugs that stay mostly in the bloodstream, so the examiner treats each substance on its own terms. The longer the gap between death and sampling, the more time drugs have to shift.
Drugs also break down or get altered. Many, including morphine, cocaine and antidepressants, slowly lose concentration in stored blood, starting within months.22PubMed. Assessing the stability of drugs of abuse and pharmaceuticals in postmortem blood samples Embalming fluid can react with drugs and cause losses, so embalmed samples are harder to interpret.23PubMed. Toxicological analysis of formalin-fixed or embalmed tissues: a review Hospital treatment or resuscitation before death can add drugs that show up on the report.24Wiley Encyclopedia of Forensic Science. Postmortem Toxicology: Artifacts Emergency teams give sedatives, painkillers and heart drugs, and these are recorded in medical files the examiner checks. A drug given in hospital is not evidence the person took it themselves.
Does a Positive Result Mean the Drug Caused Death
Not on its own. Regular users of opioids or stimulants build tolerance, meaning their bodies handle amounts that could kill a first-time user.25PubMed Central. Thinking beyond blood: brain concentrations and brain–blood ratios in postmortem toxicology Methadone levels in fatal cases and in long-term users can overlap.26PubMed Central. Thinking beyond blood: brain concentrations and brain–blood ratios in postmortem toxicology
Mixtures and genes can raise risk at lower levels. Opioids taken together can combine to slow breathing more than either alone.27PubMed Central. Trends in Poly Drug Use-associated Deaths based on Confirmed Analytical Toxicology Results in Tehran, Iran, in 2011-2016 In deaths involving extra opioids plus alcohol, the predicted hydrocodone level was only about 22% of the level seen when hydrocodone was used alone.28PubMed Central. Quantifying Enhanced Risk from Alcohol and Other Factors in Polysubstance-Related Deaths Some people also inherit a liver enzyme that turns codeine into morphine unusually fast, causing a toxic build-up from a normal prescribed dose.29PubMed Central. Pharmacogenetics and Forensic Toxicology: A New Step towards a Multidisciplinary Approach
So the examiner checks a level against ranges seen in people who died of that drug and in people who used it without harm, and those ranges often overlap. A level in the “toxic” range does not settle the matter alone, and one in the “therapeutic” range does not rule a drug out. Charts of normal and toxic levels mostly come from living patients, and after-death readings can sit outside those ranges for reasons unrelated to dose. The examiner also asks whether the amount fits the person’s known prescriptions and habits. Medical examiner guidance says a complete autopsy and the circumstances, medical history and scene are all needed to interpret toxicology.30Academic Forensic Pathology. National Association of Medical Examiners Position Paper: Recommendations for the Investigation, Diagnosis, and Certification of Deaths Related to Opioid Drugs
The autopsy contributes its own evidence. It can show natural disease, such as an enlarged heart or blocked arteries, that could have caused death with or without drugs. Fluid in the lungs is common in drug-related deaths and supports an overdose when it fits the chemistry. If the autopsy finds a clear natural cause and only low drug levels, the drugs may be listed as incidental or not at all.
On the death certificate, wording like “combined drug toxicity” means several substances together were judged responsible. A drug can be listed as contributing and not as the sole cause, and some reports find drugs that played no role at all. Families can request a meeting with the examiner to discuss the conclusions.
Poisons and Gases a Report Can Reveal
Specific tests measure carbon monoxide and cyanide from fire smoke or car exhaust.31Office of Justice Programs. Improved Postmortem Detection of Carbon Monoxide and Cyanide In a mattress fire, victims’ carbon monoxide blood saturation ranged from 10% to 43%, alongside cyanide from burning foam.32PubMed. Assessment of carboxyhemoglobin, hydrogen cyanide and methemoglobin in fire victims: a novel approach Labs can also test blood for arsenic, lead and thallium when poisoning is suspected.33PubMed Central. The undetected murder? Evaluation and validation of a practicable and rapid inductively coupled plasma‐mass spectrometry method for the detection of arsenic, lead, and thallium intoxications in postmortem blood Plant poisons such as aconitine are identified with precise testing after injury and disease are ruled out.34PubMed Central. Research progress of aconitine toxicity and forensic analysis of aconitine poisoning
Fire deaths routinely include carbon monoxide testing. Unexplained illness before death may prompt metal testing, and herbal remedies or foraged plants in the history may prompt a search for plant toxins.
Carbon monoxide is reported as the percent of the blood’s hemoglobin bound to it, not as a drug-style concentration. A high percentage in someone found in a fire suggests they were alive and breathing smoke, while a very low one suggests death may have come before the fire. The wide spread in the mattress fire shows different victims can die at different readings. The examiner also considers the person’s health, since heart or lung disease can make a lower level more dangerous.
Burning plastics and foam release cyanide, so it often appears with carbon monoxide in house fires. Cyanide levels can change after death and in storage, so labs interpret them cautiously, together with carbon monoxide and the scene. Seeing cyanide on a fire-death report does not suggest deliberate poisoning, since it can come from the smoke.
Testing After Decomposition or Long Delays
Drugs have been identified in remains found ten years or more after death.35PubMed. Postmortem toxicological investigations in cases with an extended postmortem interval and advanced decomposition Hair and even fly larvae on the body can show medications the person had taken.36PubMed Central. The combined analysis of hair samples with fly larvae for the forensic identification of skeletonized human remains But decay fluids, contamination and breakdown make it hard to say when a drug was taken or how much.37PubMed. Pitfalls of toxicological investigations in hair, bones, and nails in extensively decomposed bodies: illustration with two cases Such reports usually confirm exposure rather than explain death. The report may say substances were “detected” without amounts, and the cause of death may be listed as undetermined even with positive findings.
Hair tells a longer story. It grows slowly and traps drugs that circulated in the blood, so segments can reflect use over previous weeks or months. That helps show whether a drug was a long-term habit or a one-time exposure. Hair cannot show use shortly before death, because drugs take time to be incorporated. Hair treatments and outside contamination can also affect results.
When soft tissue is gone, bone and bone marrow may still hold traces of some drugs. Teeth, nails and muscle are other options when standard samples can’t be collected. These usually reveal that a substance was present and rarely say how much. Because they are less studied, examiners treat such results as supporting evidence.
Why the Report Takes Weeks
Labs test samples in batches, then analysts and supervisors review the data and the report for accuracy.38FOX 10 Phoenix. Why do toxicology tests take so long in death investigations? Here’s what you should know New information can trigger extra tests or sending samples to specialist labs.39FOX 10 Phoenix. Why do toxicology tests take so long in death investigations? Here’s what you should know Busy public labs serving many jurisdictions can add about 1 to 4 weeks or more of waiting.40Texas Autopsy Services. Why Toxicology Reports Take So Long: A Forensic Pathologist’s Explanation Because results may be used in court, labs cannot cut corners to go faster.41Funeral.com. Why Toxicology Results Take Weeks After a Sudden Death: Lab Steps, Bac
Legal tracking adds care too. Each sample has a chain of custody, a paper trail of who collected, stored and handled it.421800autopsy.com. What Does a Toxicology Report Show After Death? A break in that trail can let a court challenge the results.431800autopsy.com. What Does a Toxicology Report Show After Death?
Inside the lab, a sample is logged in, given an internal number, and prepared by extracting the drugs from the body fluid so instruments can read them. A second reviewer checks the analyst’s data before the report is final.
While waiting, ask the medical examiner’s office for a case number and an expected timeline. Death certificates may first say “pending” and be amended later. Families can usually request copies of the autopsy and toxicology reports, and insurance or legal deadlines can often be extended for pending causes.