Forensic Knowledge Test: What do the terms Cause, Manner, and Mechanism of Death mean?

Also, by what means can investigators and medical examiners determine the Postmortem Interval (PI), or the approximate time of death of a victim?

(Mount Wachusett Community College, 2022)

Following the death of an individual, medical examiners and investigators must determine the cause, manner, and mechanism of death. The process is conducted to provide a final determination on the case and to allow investigators to close the case, or continue the investigation. 

When we refer to cause of death, we are referring to the reason the person died. Disease, physical injuries, a stroke, poisoning, and a heart attack can all be considered causes of death. 

Manner of death refers to the ways in which a person can die, and there are four manners of death. These manners are (1) natural death, (2) accidental death, (3) suicidal death, and (4) homicidal death. Undetermined can also be used if a medical examiner is unsure of the manner of death.

The mechanism of death describes the specific change in the body that brought about the cessation of life. For example, the mechanism of death for a stabbing or shooting victim could be exsanguination, or blood loss. The mechanism of death for a heart attack could be cardiac arrest.

In many death investigations, it is important to determine the Post-Mortem Interval, or approximate time of death. Knowing approximately when a person died can aid investigators in reconstructing the events and developing a more accurate timeline of events. Examining the body for signs of rigor mortis (natural stiffening of the muscles), livor mortis (settling of the blood after death), and algor mortis (body temperature), can aid investigators in determining approximately when the victim died. Each of these techniques can be affected by the environments in which the victims were found. Therefore, it is critical that investigators possess a thorough knowledge of all three techniques, as well as how physiological changes to the body occur following death. Most importantly, it is critical that investigators thoroughly document all evidence in a timely manner, as crime scenes and the bodies of the deceased can change rapidly following death. 

References

Mount Wachusett Community College. (2022). Mock crime scene at the Mount. https://mwcc.edu/blog/mock-crime-scene-at-the-mount/

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