When laser scanners make crime scenes in Ecully speak
Access a crime scene as if you were part of the team in charge of the initial findings: at the headquarters of the scientific police, near Lyon, a unique service in France produces 3D reconstructions for investigators.
The (fictional) case: a man shot dead, another wounded by a knife. On the police officer's screen, a three-dimensional model of an apartment and three options: an empty scene, the investigation's findings (body, traces of blood, weapons, and other clues), and a video reconstructing the argument that led to the homicide.
" Our job is to facilitate understanding of the facts ," summarizes Brigadier-Chief Grégory, who does not disclose his last name. " We handle all major crime scenes ," he explains: attacks, major criminal cases, including "cold cases," those old unsolved cases.
His team thus intervened in the investigation opened after the jihadist assassination of Professor Dominique Bernard in Arras in October 2023. Or after a bomb attack in Lyon in 2019, which left around fifteen people injured, in order to verify a claim made by the suspect.
Although the cases are major, the "crime scene fixation group," according to its official name, is a small department created about ten years ago: it has only four people, one of whom specializes in 3D architecture, with experience in video game design.
But it has cutting-edge equipment, starting with two laser scanners. Equipped with a camera, they can capture a three-dimensional space and create a point cloud visualization. A constellation so fine, with an accuracy of 1 mm at 10 meters, that the scene quickly appears sharp on the screen.
The department also has a portable laser scanner, 360-degree cameras, all kinds of drones (multispectral, thermal, or conventional)... and iPad Pros that can enable this type of scanning. "I started in the police force over 20 years ago with film photos, and now we're there ," smiles Chief Sergeant Grégory.
Conversely, the locations themselves do not change. " Even if the events date back 20 years, the house ," or more generally the scene of the crime, "is still there. We can scan what exists and rework it to match the findings of the time ," he explains.
Like a footprint, for example: a composite of 150 photos can make it appear in an ultra-detailed 3D model. As a result, an investigator can go to the crime scene from their computer, zoom in on clues, and take measurements, with the impression of walking in the middle of the space, manipulating the directions to multiply the points of view.
The group is also used for animated reenactments that can be used during trials, or to popularize the role of technical experts. In the case of the Strasbourg Christmas market attack, which left five dead in 2018, they were asked to retrace the path of a defendant.
This laboratory is just a small part of the national forensic science service, which oversees more than 4,000 officers in France, including 3,140 scientists. From simple saline swabs to the latest technologies, its officers and technicians conduct more than 1.1 million analyses per year, processing approximately 310,000 seals.
In Écully, northwest of Lyon, where 1,200 of these agents work, the following services work side by side: the papillary trace research laboratory, odorology dogs, ballistics, and all the professions of personal identification.
Lyon Capitale
