The presence of the body in the trunk, first slow access blowflies to him, and then speeds up colonization by them, as the temperature in the car above the ambient temperature. This information is received by canadian scientists at “a farm of corpses” in one of the local forests and published them in PLoS ONE. Information will help criminologists to accurately establish the date of death of the victims, who after death appeared in appropriate conditions.
Forensic determine the time of death of the person according to various reports. Especially important insects: they appear on the body in a certain order, for a range of conditions known how many hours or days after the death you can expect them. These are “farms of corpses” — special areas, where different terms are placed the remains of people or animals, hours of the death are well established.
The first remains usually arrive the blowfly Calliphora latifrons and Calliphora vomitoria — sometimes within minutes after death. However, they have yet to discover the corpse. If it is somewhere close, and insects will appear later. Because of this, the estimate of time of death, and hence the date of the crime may be wrong. For a range of conditions aware of what the amendment is put on the temporary unavailability of the body for flies, but quite often the situation — the body in the trunk — in this regard, was not investigated.
Gap has decided to fill Melani Stacey (Stacey L. Malainey) and Gail Anderson (Gail Anderson) from Simon Fraser University (Canada). As an imitation of human corpses they used six bodies of domesticated pigs. Three they closed in the car trunk in one of the forests of British Columbia 45 kilometers from Vancouver. Two cars stood in the shadows, one was protected from the sun. Three more corpses were placed on earth in cells that do not prevent the access of insects, but protect from bears and raccoons. All animals had a similar weight (25 to 32 kilograms) and was equally dressed in a human shirt, shorts and pants.
The temperature in the cars was measured every hour automatic thermometers installed in the trunk and in the cabin. However, in the process of monitoring all devices in the trunk out of order. The same thermometer was lying in the cells. The researchers twice a week and recorded the status of each body: the degree of decomposition, presence of those or other insects, their age (adult, pupa, or larvae, if the larvae, at which stage).
The first three days of decomposition of bodies in the trunks was slower than in the open countryside, and the larvae of flies of the genus Calliphora in cars is not found. Larvae of other blowflies, Protophormia terraenovae, was there later than in the cells. However, by the end of the first week the bodies of the cars were in the later stages of decomposition than the body cells. Most likely, this contributed to elevated temperatures in vehicles: it accelerated the development of larvae of Protophormia, but prevented Calliphora (these insects prefer cooler areas). Although due to the failure of accurate thermometer readings for Luggage was available in the interior of the car was 10-20 degrees warmer than outside, and in other parts of the machines, most likely, too.
The body of one of the cars insects began to settle almost immediately, but their number was significantly lower than in other cases. Probable cause was found out later. It turned out that this car between the cabin and trunk was installed metal fire screen. He could keep the smell, which flies find rotting corpses. In the two remaining machines of the insect were significantly more than the bodies in the cells. Perhaps the high temperature in the trunk was strengthened by the spread of odors, which attract flies. Interestingly, in homes, on the contrary, the bodies of colonized insects less than if the corpses are outside of buildings.
It turns out that in determining the date of death of the victim was found in the car, you need to compare data on what insects are present on the body, with information about the temperature in the car. If it is unavailable, you can try to extrapolate data from the nearest meteorological stations. Otherwise, entomological examination may be mistaken for a few days both upwards and downwards — depending on when found dead.
Forensic science is closely linked with biology and chemistry, and new methods of science help solve crimes. So, the concentration of certain substances in the blood recently possible to determine the time of death of a person by the proteins in the composition of the hair — to establish his identity, and in the aggregate of bacteria on the smartphone or the sole of the shoes — may be to track the movement of the individual.