Forensic Toxicology Procedures - Collecting Toxin Samples From Corpses

When somebody is poisoned to death, a forensic medical examiner/toxicologist must undergo the hard job of determining what the poison was that killed the victim.

The reason that poisons are very popular is because they can be hidden. Toxic substances very rarely leave clues visible to the naked eye. Therefore finding a toxin is a difficult task that requires several specialized tests and involves a variety of bodily fluids and tissues.

The best hiding places for these toxins are places where chemicals enter the body, where chemicals congregate within the body, and along the thoroughfares of elimination. Therefore stomach contents, blood, and tissues surrounding needle injection sites may contain high doses of the toxic material. Analyses of brain, liver, and other tissues can disclose to the medical examiner where a drug or its metabolites accumulated. Finally, a urinalysis can be indicative of where the toxic substance and its products of metabolism are concentrated for final elimination. Here is a list of potential "hiding" places for illegal toxic substances:


Blood: Blood is perhaps the forensic toxicologist's most useful tool for finding toxins. With present day toxicological procedures, one can find essentially any drug and its major products in the blood. A blood exam tells the toxicologist what was transpiring in the body at the time of death. Concentrations of medications and drugs within the blood are proportional with the levels of intoxication and with levels that can potentially kill a person.
Stomach contents: Hospitals normally "pump" the stomach contents of survivors of drug overdoses by way of a gastric tube that is inserted through the nostril and into the stomach. Once the contents are extracted from the stomach, they are washed to remove any stomach acids and tested for the presence of drugs or poisons. During an autopsy, forensic medical examiners test the stomach contents in the same manner. Getting stomach contents is crucial where criminal investigators suspect poisoning or drug overdose. Concentrations of any drugs found in the stomach are not necessarily proportional with their levels in the blood and thus their effects on an individual.
Urine: A urinalysis is commonplace for workplace drug testing. It can also be useful during an autopsy. Since the kidneys serve as a major depot for the body's drug and toxin elimination routes, forensic medical examiners/toxicologists can many times find such toxic substances in greater concentrations in the urine. However, the relation between urine concentration of a drug and its effects in the body lacks proportion. This means that the urine level may disclose that the toxic substance had been in the blood at some earlier time. It does not determine whether the drug was exhibiting any effect on the person at the time it was collected.
Hair: Hair has the unique ability of providing an intoxication timeline for many toxic substances including lead, arsenic, and other heavy metals.
Vitreous humor: Within the cavity of the eyeball, there is a liquid called vitreous humor. This liquid does not putrefy easily like the other tissues of the body. In severely decomposed bodies, this fluid may be what is left of a body that can be tested. Concentration levels of drugs within the vitreous humor may lag behind the drug concentration levels found in blood by about 1 to 2 hours. Therefore, testing the vitreous humor reveals the concentration of a toxic substance in the blood 1 to 2 hours prior.
Liver: The liver functions to metabolize (breakdown) drugs and toxins. Testing the liver and the bile that it produces many times discloses the presence of a drug or its metabolites, the products of drug metabolism. Forensic investigators can measure drug concentrations in the liver since many drugs, especially opiates, can be found in the liver and bile, even when blood tests yield no presence of drugs. The liver may show drug concentration during the hours prior to death, and the bile may tell what drugs were present in the system during the past three to four days. However, neither test is accurate.
Insects: Forensic scientists may test insects that eat up dead bodies for drugs in the event of severely decomposed bodies. Since particular drugs tend to reside in the tissues of these bugs, they may provide information about whether a drug was present in the victim.

These locations are the most common locations for finding evidence of drugs or other toxic materials in the event of a suspected homicide.