The most important function of the medical examiner in any death investigation is determining the cause, mechanism, and manner of death. Here are definitions of each of these terms:
Cause of death: The disease or trauma that directly caused the victim's death. Examples include a heart attack, a gunshot wound to the head, or a drug overdose.
Mechanism of death: The specific physiological derangement that actually led to the cessation of life. For example, a heart attack victim could die from a deadly change in heart rhythm or from severe damage to the heart muscle, leading to shock. Here the cause of death is a heart attack, but the mechanism is a cardiac arrhythmia or cardiogenic shock, respectively.
Manner of death: How the cause of death came about. The five manners of death are natural, accidental, suicidal, homicidal, and undetermined. A gunshot wound (the cause of death), may have been accidental, suicidal, or homicidal, for example. Only deaths from disease are natural.
