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Decomposition and preservation — autolysis, putrefaction, adipocere and mummification

After death the body breaks down by two processes — autolysis from the cells' own enzymes and putrefaction from gut bacteria — and the rate is set mainly by heat, moisture and access to air, while special conditions replace decay with preservation: adipocere in moist surroundings and mummification in dry ones.

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Why it matters in the exam

Questions ask the student to identify the stage from a description of the body, to choose the conditions that lead to adipocere or mummification, and to recognise misleading findings. The first external sign of putrefaction is usually greenish discolouration of the right lower abdomen, over the bacteria-rich caecum, usually 24–72 hours after death in a temperate climate. Next comes marbling — a network of green-brown superficial veins from haemoglobin breakdown — followed by gaseous bloating, mainly of the face, genitals and abdomen, with blood-stained purge fluid from the mouth and nose, skin slippage and blisters.

These findings mislead: blood-stained fluid from the nose does not indicate injury, the tongue and eyes protrude because of gas and not because of asphyxia, and pink teeth are seen in bodies where the head lay low, mainly in drowning and decomposition. Heat accelerates decomposition, cold slows it, and a body is best preserved in the cold. A familiar rule of thumb says that decomposition in air is 2 times faster than in water and 8 times faster than in earth burial; it is only an approximation. Obesity, infection, sepsis and open wounds accelerate decay.

Adipocere forms by hydrolysis of body fat into fatty acids, in moist, oxygen-poor surroundings such as water or a wet grave; it needs weeks to months and preserves the body shape and sometimes wounds. Mummification is desiccation in hot, dry, ventilated surroundings; the skin becomes hard and brown and the organs shrink. Embalming introduces formalin and other agents into the vessels, alters tissue appearance and hampers some toxicology tests, so when a crime is suspected samples must be taken before embalming.

Key points

• Autolysis from cell enzymes; putrefaction from gut bacteria.
• First sign: greenish right lower abdomen.
• Heat accelerates, cold slows; rule of thumb: air 2 times water and 8 times burial.
• Adipocere: moisture and low oxygen; mummification: heat and dryness.
• Embalming hampers testing; sample before it when a crime is suspected.

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Sources

• Knight's Forensic Pathology, 4th edition (2016) — Decomposition and modified decomposition
• Simpson's Forensic Medicine, 14th edition (2020) — Changes after death
• Spitz and Fisher's Medicolegal Investigation of Death, 5th edition (2020) — Postmortem changes and artifacts

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.