Insect larvae, rigor mortis and the colour of a body.

These are three of the elements forensic investigators can use to determine the time of death and how long a body has been at a crime scene.

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According to Professor Gert Saayman, head of the department of forensic medicine at the University of Pretoria, forensic pathologists visit crime scenes to find information about the body that places findings during the autopsy in context.

"It is ideal to examine the body as soon as possible. Within 24 hours after death would be the best. After death the body starts cooling at a relatively constant speed, rigor mortis takes place, and discolouration starts setting in."

The stiffening process
The smaller muscles in the face and between the fingers start stiffening between two and four hours after death. The bigger muscles in the arms and legs stiffen between four and six hours after death. After six to eight hours the whole body is stiff and it remains this way for 24 hours before it relaxes again for the last time. During Highveld winter conditions bodies can remain stiff for a couple of days on end.

Saayman says investigators can also determine if the body was moved after death by checking to see if the stiffening process was interrupted.

"If the discolouration of the body and the stiffening do not correspond with the position in which the body is found, for instance, the body might have been moved. The pattern and distribution of stiffening can also point to the fact that it had been moved."

Factors such as the day and night temperatures in the area where the body was found could influence the tempo at which the body cools and hamper pathologists' task. He says cold, dry air during Highveld winters ensure a body remains relatively intact but at the same time cause confusion about the time of death.

Insects' life cycle studied
"Forensic entomologists will study the insect larvae that hatch after eggs are laid and infest the body. They then determine the time a body has been in a certain spot by studying the insects' life cycle."

While the body starts decomposing externally within a day or two, an internal digestion process takes place when the enzymes start breaking down the organs. Saayman says bodies start developing a decomposing smell after three to five days in winter.

DNA samples, tissue and wounds found on the body can give the investigators further clues about the circumstances surrounding someone's death. – (Borrie la Grange, Beeld)
 

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