Essonne: behind the scenes of the new technical and scientific police laboratory

A brand new tool to make the invisible visible, at the service of investigators. At the Évry-Courcouronnes Police Hall (Essonne), the five technicians from the technical and scientific police have a new technical platform allowing them to search for fingerprints (or papillary marks) in the frame criminal and misdemeanor cases followed by the Essonne judicial police as well as the national police districts of Évry-Corbeil, Val d’Yerres – Val de Seine and Étampes.

1.2 million euros invested to demagnetize, refit and re-equip

After three and a half years of work for an investment of 1.2 million euros, including 500,000 euros delivered by the State, the technical platform was able to reopen its doors in March.

“The old technical platform was not adapted to forensic activity. Above all, it was extremely dilapidated, so much so that conditions had become dangerous for staff. We had to demagnetize everything, rearrange everything and re-equip everything,” recalls Dorian, the head of the conventional criminal section of Évry.

Every day, technicians are responsible for process judicial seals that they receive after they have been collected at crime scenes by police officers deployed on the ground.

The expert eye of police officers put to use

Following the strict disclosure protocols set up by the National Forensic Police Service, the five technicians stationed in Évry implement different papillary trace detection techniques.

“For the moment, we only apply our revelation techniques on non-porous supports such as plastic, metal or glass. But by 2025 at the latest, we will also be able to process porous supports, therefore paper or cardboard, for the entire department,” explains Dorian.

Once out of the storage room, the seals will be broken for the first time in the photo room.

“It was in this room that the objects were taken out for the first time since their packaging at the crime scene. Each object is carefully observed, described and photographed »summarizes Dorian.

Light, the first ally in fingerprint detection

Once this formality has been completed, the technician carries out a optical detection papillary marks on the object in question, whether they are visible to the naked eye or, on the contrary, whether they are latent.

In white light, it is possible that no papillary marks can be seen on an object. However, this same object, passed under UV light, will reveal papillary marks visible to the naked eye which we will photograph and can potentially improve in order to obtain usability.

“It is a technique which is not not destructive neither for the trace nor for the supportwhich therefore allows biological samples to be taken subsequently,” adds the police officer.

Traces can also be revealed using a chemical process

In another room of the laboratory, Essonian technicians also have the possibility of revealing papillary marks on objects via chemical detection, by placing them in a cyanoacrylate tank.

Cyanoacrylate is a glue. By heating it in the tank, vapors will diffuse and settle on the papillary marks present on the objects and color them white. Once the traces are revealed, we stop the fumigation.

The process lasts around ten minutes. A witness trace is also placed in the tank by the technician to ensure the quality of the result.

Dactyloscopic powders used to increase contrast

The objects are then taken out of the tank and a careful observation papillary marks revealed by fumigation is carried out.

“If the traces are conclusive, we take photos of them for exploitation. If the contrast is not very good, we will reinforce it by applying powders luminescent or black depending on the support on which the trace is found,” continues Cindy.

“All the analyzes that we carry out here are traced just like the consumables that we use to, in the event of a problem, identify the stage where it appeared, certifies Dorian. It’s like in the food or pharmaceutical industry.”

Useful in criminal investigations and for everyday delinquency

« On a des high level technicians, we needed a tool that was up to their standards,” underlines Jean-Marc Luca, departmental director of public security for Essonne, on the occasion of the inauguration of the new technical platform on June 10, 2024.

“It is an essential tool in criminal investigations. DNA, papillary marks, scientific cross-checks, it’s what leads to convictions at the hearings, whether in correctional or in the criminal court,” continues the boss of the Essonne police officers.

For the prefect of Essonne, Frédérique Camilleri, this “new cutting-edge equipment is of course useful for solving criminal cases, but it also has an effect on delinquency that concerns everyone.”

“It helps to stop burglars, serial attackers and even crooks who prey on the elderly. What then allows victims to have an author face to face in court and obtain compensation,” highlights the state representative.

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