TIME SiNCE DEATH
There are changes that occur to the body very soon after death that can provide a very precise postmortem interval. Some of these include stiffness of the muscles (rigor mortis), cooling of the body
temperature (algor mortis), and pooling of blood based on gravitational forces (livor mortis). Since these changes are associated with the first 48 hours after death, it would be unusual for a Forensic Anthropology Forensic Anthropology" href="/forensic/nn.html">forensic anthropologist to be consulted in such cases. As the putrefactive changes advance, the time since death estimate gets less precise. Estimates at this point are based on the degree of decomposition associated with the body and are more within the scope of a forensic anthropologist's expertise. Depending on the amount of time that passes between death and discovery, a body may be encountered that is fresh, bloated, mummified, skeletonized, or in a combination of these states.
There are many variables associated with decomposition rates. Time is obviously one vital component, but the two most critical are climate and context. Climate is important, since cold weather will slow the decomposition process. If temperatures are low enough, a body may be preserved for years or even centuries. Warm and humid climates will accelerate decomposition rates, and it has been shown that a body can become completely skeletonized in as little as two weeks.18 Hot and dry climates have the tendency to preserve bodies through natural mummification.
Closely tied in with the climate are the insects that feed on human remains. Forensic entomology is a specialty that studies the progression of insects associated with a decomposing body. The presence of insects can be a good indicator for the time of death, since different insects will be present at different stages of decomposition. Most notorious are the flies, which can be observed to land on a body within minutes of death. Also, scavenging carnivores may impact a body, and studies have shown that there is a natural progression associated with carnivore scavenging that can be correlated with time since death.19,20
Consideration of the context of a body will greatly affect the time since death estimate. For example, was the body buried, on the ground surface, in the water, in a shaded environment, in direct
- Figure 6.6 At the Anthropological Research Facility (pictured above), forensic scientists study the decomposition of the human body.
sunlight, in a locked and secured apartment, or in a plastic bag? You can imagine any number of scenarios, each one of which will have an impact on decomposition. It is precisely because of these variables that it is difficult to develop a "cookbook" approach to the interpretation of the postmortem interval. As a rule of thumb, it has been suggested that the degree of decomposition observed on a body on the surface after one week would take two weeks if the same body was placed in water and eight weeks if the body was buried.21
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