Post-mortem interval

This article is about forensic science. For Rosicrucian death practices, see Rosicrucianism § Preservation period after death.

Stages of death
Pallor mortis Algor mortis Rigor mortis Livor mortis Putrefaction Decomposition Skeletonization

Post-mortem interval (PMI) is the time that has elapsed since a person has died. If the time in question is not known, a number of medical/scientific techniques are used to determine it. This also can refer to the stage of decomposition of the body.

Types of change after death

Many types of changes to a body occur after death. Some of those that can be used to determine the post mortem interval are:

• Algor mortis - body cooling;
• Livor mortis - settling of blood in the lowest-placed parts of the body;
• Rigor mortis - stiffening of limbs;
• Forensic entomology - insect (especially blowfly) activity on the corpse;
• Vitreous humour changes - eye chemistry;
• State of decomposition - autolysis (process of self digestion) and putrefaction (process caused by bacteria found within the body).

Traditional decomposition stages

A person who judges the time of death by the means of decomposition can refer to a simple five-stage process:

• Stage 1: Initial Decay - Bacteria located mainly in the lower intestine begin decomposition, giving a greenish color to the lower abdomen.
• Stage 2: Putrefaction - Bacteria grow throughout the body, releasing gases, which in turn bloat the body and cause unpleasant odor.
• Stage 3: Black Putrefaction - This stage brings further discoloration to the body. The gases from bacterial decay begin to escape, causing strong odor.
• Stage 4: Butyric Fermentation - The internal organs liquefy and the body begins to dry out.
• Stage 5: Mummification - This is the slowest of the five stages. In a hot, dry climate the body may dehydrate, inhibiting bacterial decay; the skin dries to a dark leathery appearance.

More advanced methods

More advanced methods include DNA quantification, infrared spectroscopy. and for buried individuals changes in soils such as the levels of methane, phosphates and nitrates, ninhydrin-reactive nitrogen, volatile organic compounds and water conductivity.