Postmortem Toxicology: The Basics

Most often, I am asked by attorneys to review cases that involve the living. But at times, I am asked to review cases that involve the dead, and the question becomes: what happened before death? Specifically, what was the role, if any, of the drugs/chemicals/toxins found in the decedent’s body according to postmortem toxicology testing? Examples of such cases include those involving death following drug delivery, medication-related deaths, and fatal accidents (motor vehicle or workplace) following drug or alcohol use.

When it comes to drugs, it’s not straightforward (and at times, not possible) to determine what amount of drug was used prior to death. In my CLE talk “Postmortem Toxicology for Attorneys: What Can Dead People Tell Us?”, one of my main take-home points is that if all you have are postmortem drug levels, then all you have are … postmortem drug levels. I know, that sounds simplistic. But, it sums up the main point I want to make regarding such levels. There are published tables of postmortem blood concentrations for numerous drugs in the medical and forensic literature. The existence of such tables have created the expectation that one can simply look up drug levels on these tables, compare them with those from a postmortem toxicology report, and voilà! … determine if the drug was taken antemortem (before death) in a therapeutic, toxic, or fatal dose. Those tables have their time and place. However, they are not meant to be used in isolation but rather simply as the starting point of a toxicologic investigation. “User beware”.

There are numerous variables that can influence postmortem drug levels, making these published tables only a reference source. As a toxicologist interpreting postmortem drug levels, I want to hear a “story”. This story should include as many of these chapters as possible: the decedent’s medical history (eg, medical conditions, medication history, drug abuse history), information from the scene (eg, drugs, drug paraphernalia), witness accounts (what was the decedent’s behavior prior to death?), police reports, autopsy findings, when the postmortem samples were collected, the location from which the postmortem samples were collected, and the circumstances of death. There of course can be other chapters to this story (these are just a few). But I list these to illustrate that reliable interpretation of postmortem drug testing results hinges on more than just drug levels.