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Forensic Entomology


Franco Zecchin

The Entomology Department of the Criminal Institute of the <Gendarmerie> is a world premiere. Flies hummed upon the putrid belly, Whence larvae in black battalions spread And like a heavy liquid flowed Along the tatters deliquescing In The Flowers of Sickness, Charles Baudelaire, describes a madly buzzing ballet around a decomposing corpse. Entomological experts, however, detect a choreographed study in chronological timing that has unlocked many a murder mystery. Insects prove excellent "witnesses" in helping investigators determine the post-mortem interval - that is, the time elapsed between moment of death and discovery of the body. Rosny-sous-Bois. When a human body draws its last breath in the countryside, a virtual alarm clock sounds in the insect world. The flies, which are able to smell a body up to 3 kilometers away, are the first to arrive, predictably within minutes to lay their thousands of eggs. Later, other kinds of flies appear, then the beetles. And so it goes, with different families of insects showing up to punch the clock for their pre-assigned shifts. Insects can either eat, mate, breed their progeny, find protection or even hunt on a cadaver. The average person simply sees a madly buzzing ballet around a decomposing corpse. Entomological experts, however, detect a choreographed study in timing that has unlocked many a murder mystery. Insects prove excellent "witnesses" in helping investigators determine the post-mortem interval - that is, the time elapsed between moment of death and discovery of the body. Given the chronological precision in which the various insect species come to colonize the corpse, forensic investigators can ascertain the date of death with incredible accuracy. “For example, when a cadaver is found six months after death, we can pinpoint the date of death to the week. In other words, we can narrow it down to within a day per month of the corpse's age”, says Lt. Emmanuel Gaudry, the head of the Forensic entomology department, at the Criminal Research Institute of the French Gendarmerie (IRCGN), located in Paris suburbs. In other cases, such entomological techniques can also prove that a body has been moved after death. Such conclusions require meticulous and lengthy analysis not only to identify the insect species sampled at the crime scene but also to know all the environmental factors since the death, such as temperatures and humidity, which greatly determine the state and the speed of decomposition as well as the speed of growth of each insect species. This scientific technique is now irrefutable in courts and well accepted by most major police forces in western countries, although there is no school of forensic entomology in the world. The French gendarmerie (French police corp) of the IRCGN, which has just celebrated its tenth anniversary, has the world's first entomology laboratory in a national institute of criminology established in 1992. © Text: Frédéric Castel.



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