An autopsy is a thorough examination of a person's body after death to try to determine the cause and manner of death. While the physician performing the autopsy (the forensic pathologist) can see the body's organs and look for natural causes of disease and death, some agents---such as drugs or other toxins---cannot readily be seen, and a toxicologist needs to examine blood and tissue samples to determine the cause of death.
The autopsy report is prepared by the forensic pathologist---a physician who performs autopsy investigations. Results of an autopsy are generally quick because the pathologist is noting problems or issues that can be seen and confirmed in his or her laboratory.
The toxicology report is prepared by trained and certified medical technologists, clinical chemists or pathologists who specialise in toxicology. They test for a variety of toxins, including natural toxins (such as those associated with poisonous plants or animals), chemicals found in the environment, alcohol and drugs (both prescription and illicit).
When Do You Need Both?
Sometimes an autopsy report is inconclusive. In other words, the cause of death is not immediately known and the forensic pathologist needs to run additional toxicology tests to determine if drugs or other toxins led to or contributed to a person's death. Sometimes a forensic pathologist can tell how a person died---for example, cardiac arrest---but they need a toxicology report to tell them why a person died.
Toxicology reports are routinely performed in suspicious deaths where law enforcement is involved, but they are not as frequently seen in hospital autopsies (where a person dies in the hospital and the family requests an autopsy).
If an autopsy report is inconclusive and a toxicology report has been ordered, a death certificate with the cause of death listed as "pending" may be issued because it can take several weeks to get the results of a toxicology report. As soon as the toxicology report is back and a cause of death is known, the death certificate is amended to show cause of death.
Why Do Toxicology Reports Take Longer?
It can take weeks to get a toxicology report for several reasons, including the wide range of toxicologic specimens that must be tested for, the complexity of the tests themselves, communication between the toxicologist and forensic pathologist during the investigation, and the amount of time it can take to gather all of the information from the various individuals working the case.