Decomposition Begins at the moment of death, caused by two factors Autolysis The breaking down of tissues by the body's own internal chemicals and enzymes Putrefaction The breakdown of tissues by bacteria These processes release gases that are the chief source of the characteristic odor of dead bodies These gases swell the body

Decomposition Scavengers play an important role in decomposition Insects and other animals are typically the next agent of decomposition, if the body is accessible to them The most important insects that are typically involved in the process include the fleshflies (Sarcophagidae) and blowflies (Calliphoridae) The green-bottle fly seen in the summer is a blowfly Larger scavengers, including coyotes, dogs, wolves, foxes, rats, and mice may eat a body if it is accessible to them Some of these animals also remove and scatter bones.

Factors Involved in Decomposition In a roughly descending degree of importance, those factors include: Temperature The availability of oxygen Prior embalming Cause of death Access by insects Burial, and depth of burial Access by scavengers Trauma, including wounds and crushing blows Humidity, or dryness Rainfall Body size and weight Clothing The surface on which the body rests

Differentiate between PMI and Time of Death These may not always equate. Post mortem interval is restricted to the time that the corpse or body has been exposed to an environment which would allow insect activity to begin. Closed windows Body in box or bag Cold temperatures Deeper burial

Major Groups of Insects Associated with Cadavers Flies Blowflies Flesh Flies House Flies Cheese Skippers Beetles Carrion Beetles Dermestids Scarab Beetles

Blow Fly Metamorphosis Adult Pupa Eggs 3rd Instar Larva 1st Instar Larva 2nd Instar Larva It takes approximately 14-16 days from egg to adult depending on the temperatures and humidity levels at the location of the body. Image: http://www.umext.maine.edu/images/FlyLife.jpg Information: http://www.kathyreichs.com/entomology.htm and http://www.forensicentomologist.org/

Decay Rates Are Variable Studies of decay rates of 150 human corpses at in the Anthropological Facility in Tennessee (The Body Farm) Most important environment factors in corpse decay: Temperature Access by insects Depth of burial Other Factors Chemical-- embalming agent, insecticides, lime, etc. Animals disrupting the corpse

Determining Whether the Body has been Moved Insects present on the deceased body that are not prevalent to the crime scene can indicate that the victim was murdered elsewhere and was dumped at another location

Drugs Insects that feed on the body of individuals that have been poisoned can be examined to determine what type of drug or toxin the person was poisoned with It is important to note that specific drugs either speed up or slow down larval development Can influence entomologist’s final report

Challenges to Forensic Entomology 3 challenges exist Temperature Temperature of crime scene and the temperature that the insects have been exposed to us unknown Season Entomology is valuable only in spring, summer, and fall Exclusion of insects Insects are excluded based on condition of body