This is a small laboratory, located in the heart of the pôle judiciaire de la gendarmerie nationale in Cergy-Pontoise (Val-d’oise). Its local to the walls in immaculate evoke those of a clinical. All the more that you’ll meet men and women in white coats, sometimes hunched over a microscope. At the end of a hallway opens to a large room in the center of which sits a bed of stainless steel. On a tray on wheels, surgical instruments. The place is not an operating room but… dissection. It is here that the forensic pathologists conduct autopsies of the bodies, including the suspicious death requires investigation. In a room adjoining, three freezers hold in the cold the organic elements collected for investigation purposes. Six scientists working here, moving through France at the speed of business. They treat a few hundred cases per year. What makes the department “Wildlife Forensic” of the Institute of criminal research of the gendarmerie nationale (IRCGN) is the first european center accredited in this field.
Laurent Dourel, 46 years old, heads the department of Wildlife Forensic (3F) of the IRCGN since 2013.
© Romain GAILLARD/REAÀ a few days of his transfer to the section of legal support of the region of Île-de-France, Laurent Dourel a tour of the premises. The commander, 46-year-old, originally from toulouse, leads the ” 3F “, as they called this department in the police. The expertise of this laboratory, forensic entomology is recognized in the world. The foreign policies of the consult. Including to the FBI ! The novelist of scotland Val McDermid has recently sought the advice of the French team in order to verify the veracity of the police story of one of his latest thrillers.
But the main “clients” of the centre remain the judges, who assign to the biologists of the department, “Wildlife Forensic” the task of determining the date of a death and its cause. It is also, sometimes, its biologists that the responsibility to designate the suspects when the facts prove to be of criminal origin. On average, a half-dozen human corpses are discovered every day in our country. If the vast majority of these deaths are natural or accidental, it happens, however, that some are not. It is then that come on to the scene of the 160 investigators of the IRCGN, the first chief of which the cell 3F.
Flies and green kepis bleus
“Here are a few of my investigators,” smiles Laurent Dourel by designating a small window where are pinned insects of different species. The squadron leader takes us in another room, where he shows us flies, live ones, in Tupperware boxes, maintained at a constant temperature (24 °C). “After a period of 72 hours, the forensic medicine is no longer able to date the time of death, we pass over to these small animals,” says the forty-something woman.
The technique was developed at the end of the Nineteenth century. In 1894, Jean-Pierre Mégnin published a classification of insect scavengers. This former veterinarian has noticed that many species follow one another on the corpses, in eight successive waves. These “death squad” are mostly diptera (flies), but also beetles and even lepidoptera, in other words, butterflies. Mégnin think a good idea to use this succession of insects to determine the chronology of a death. He is right. The technique proves to be very reliable. “We can date one or two days near the time where there has been a death, and up to eight months after the death,” says Laurent Dourel.
the logo of The department, “Wildlife Forensic” ” (3F) represents a fly…
© Romain GAILLARD/REAL’observation the pedigree of the insects is, since then, become a priority of the investigators (in the same way that the statement, fingerprints and traces of DNA) when the discovery of a body. From the moment of death, flies are common, gray or black, affluent and colonize the remains. They give way to their cousins in the back blue or green, attracted by the odor emitted by the putrefaction of the flesh. A third species arrives when the fat of the body begin to ferment. And then a fourth, at the time of the degradation of the proteins contained in the muscles. A fifth squad is irrepressibly drawn by the smell of ammonia, which then releases. Another species the tip of the nose when the stage of decomposition is more advanced. The last two, like ants disguised as beetles, finish cleaning the body, until there is hardly anything on the skeleton.
of Course, some species can be crossed, or even mix. The investigators are then decant things. “We take the ground out from under the body. In general the moths lay there eggs, which develop by feeding on the organic elements present on the spot. We are waiting for two to three days, the hatching of the pupae (the larvae of flies) and observe the species that comes out of it. According to which, we have items dating to be very precise, ” says Laurent Dourel.
insects, but also… micro-algae
These explanations, a strand glaçantes, the policeman with the look of Kojak (face affable, skull receding hairline) delivers without missing a beat. For the past six years that the squadron leader is working here, Laurent Dourel recognizes itself ” (s)relationship with death has changed.” He confesses to being shielded internally. In his eyes, ” the hardest part, however, is not the scene of the crime, but rather the discovery of a small grandma passed away in her home, forgotten by all. And of course the disasters involving a large number of killed “, he continued. The scientist has worked both on the identification of French victims of the 2004 tsunami in South-East asia and on the air crash of the flight 9525 of the Germanwings in march 2015. “Experiences hard have left traces “, draws coyly the person concerned.
Sampled under the dead bodies, the larvae of diptera are set to hatch in a casing air-tight. When they come out of their “pupa” – their cocoon, the insect immediately fell asleep and then killed. They “speak” then under a microscope.
© Romain GAILLARD/REAL’man has not always worn the kepi. After a course at the school of agronomy and a graduate in biology carried out at the university of Corsica, the son of a policeman has certainly done his military service at the IRCGN, but he began his professional career with DuPont de Nemours. “I was developing, among them, insecticides to protect the crops,” he says, amused to work today with the animals he chased in the past. Tired of chaining fixed-term contracts, he decided to join the public service and integrity and, by competition, the school officers of the national gendarmerie in 2002. He landed at the IRCGN. The service is then installed at the fort of Rosny (Seine-Saint-Denis). It will take the direction in 2013 and will be moving, two years later, the laboratory in Cergy-Pontoise, in the local brand new built in the place of a former military barracks.
A wide range of bio-indicators
the work of The biologists of the department, “Wildlife Forensic” cannot be reduced to culture flies. “We are interested in all the bio-indicators that provide information on the conditions of death,” continues the officer of the gendarmerie. Ansi is-t-he of diatoms, micro-algae, whose presence in the tissues (the lungs but also the liver) is used to determine if an individual is death by drowning. “For the moment, this technique, developed in the United States during the last war, is only valid for the deaths that have occurred in the fresh water. But we are developing today a variant that could be applied to the detection of drowning at sea “, complements the major Jean-Bernard Myskowiak. Some murderers who throw their victim to the water, hoping to make it look like an accidental death, and thus could be confused.
In the same spirit, Lawrence Dourel is also interested in pollen. “They can often play the role of a marker to help us locate the place where the death occurred. Or the scene where the suspect is past, ” he continued. This investigative technique has been developed since 1959 to determine whether a body has been moved.
other micro-organisms could be mobilized shortly. “We are interested in intestinal microbes and bacteria with, each time, the same idea : identify ways in which these bio-markers may be useful to our investigators,” says Laurent Dourel. After conducting extensive research on human genetics for identification purposes, the researchers of the department 3F of the IRCGN focus now as much on the exploitation of the DNA non-human. “It may be of vegetable or animal origin, a trace of genetic found on a body opens infinite possibilities to the investigators,” says the commander Dourel. A day may come where cats, dogs and even ficus to become “witnesses in court” !
Read also when the cybergendarmes patrolling the ” dark web “.
On the same subject, Philippe Charlier, the man who made the dead speak