Post-Mortem Changes

• Initial Post-Mortem Changes – The Mortises

  •The Mortises are a set of three changes that occur during the very early stages of decomposition.

  •Livor Mortis

  •The settling of red blood cells within the tissues and vessels of the body according to gravity.

  •Coagulation of blood results in the gradual “fixing” of lividity.

  •Can be used to indicate positioning of a body or the presence of intermediate objects due to bleaching.
• Initial Post-Mortem Changes – The Mortises

  •Algor Mortis

  •The change in temperature of the body to match the ambient temperature of the environment in which it is deposited.

  •In most cases, will result in cooling of the body, which occurs at approximately 1°C/hr for the first 12 hours

  •Rate of temperature change is dependent on the temperature gradient between the body and the surrounding environment.

  •Can be used to estimate post-mortem interval based on Henssge’s nomogram

  
• Initial Post-Mortem Changes – The Mortises

  •Rigor Mortis

  •Rigor Mortis is the gradual stiffening of the muscles after death

  •Results due to build up in Adenosine Triphosphate (ATP), which causes contraction of the muscle fibres.

  •Once ATP is broken down, rigor eases and the body returns to its flaccid state.

  •Begins in the small muscles and progresses to the larger muscles

  •Can be used to estimate post-mortem interval, although not precise.

  
• Marbling and Blistering

  •Marbling is caused by the progress of sulfhaemoglobin through the vascular system.

  •Results in progressive discolouration of the body, with dark tracks showing the progress of the sulfhaemoglobin through the body.

  •Often accompanied by the beginning of bloating of the abdominal cavity.

  •First observed in the abdomen, particularly in the region of the upper right quadrant.

  •Skin blistering occurs as a result of separation of the outer layer of the epidermis from the underlying skin layers.

  •Eventually, the epidermis will slough away, called degloving.
• Bloating and Purging

  •Bloating of the body cavities occurs due to the production of decomposition gases

  •Gases are Volatile Organic Compounds (VOCs) and include cadaverine and putrescine.

  •Build up of gases in the abdominal cavity spreads to the thorax and through the inguinal canal to the tissues of the genital area.

  •Eventually, the gases will purge through body cavities, along with any fluids that have built up within the body cavities.
• Saponification

  •Saponification results from the hydrolysis of body fats

  •Requires the presence of some water, although studies have suggested that the quantity of water within the body may be sufficient in some cases.

  •Frequently seen in bodies recovered from water after a period of time e.g. reservoirs, the sea, rivers or ponds.

  •Creates a waxy residue which forms an anaerobic environment – restricting activity of aerobic bacteria

  
• Dehydration - Mummification

  •Dehydration removes access to water for bacteria, resulting in slowing of the rate of decomposition or eventually, the arrest of decomposition.

  •Dehydration through high temperature and low humidity results in mummification

  •Frequently observed in sand burials from North Africa

  •Can also occur in temperate climates where remains are exposed to a constant movement of dry warm air
• Dehydration - Freezing

  •Freezing, like mummification, removes access to water.

  •Over time, this results in a drying out of the tissues, an arrest of decomposition, and preservation of the remains.

  •Observed in sailors from the Franklin Expedition to find the Northwest Passage

  •Sailors buried in the ice around the arctic circle preserved for hundreds of years.

  •Another example is that of Otzi, whose remains were preserved in the ice of the Italian Alps for over 5000 years.