More than a year after the creation of a pole specializing in cold cases in Nanterre, and while hundreds of criminal cases remain unsolved, scientific and technical progress appears as hope for resolving certain old investigations.
In France, hundreds of criminal cases remain unsolved. They are called “cold cases” and since March 2022, a specialized center in Nanterre has been in charge of these files. For a long time, it was complex to make the evidence speak years after the fact, and it was necessary to hope for a miracle to solve certain crimes. From now on, scientific and technical advances make it possible more and more often to advance investigations.
With its laboratories, the Criminal Research Institute of Pontoise, for example, plays an important role, as its boss, General Gilles Martin, details: “The queen of evidence is science, it is no longer confession as in the time of Commissioner Maigret. Previously we needed a bloodstain the size of a two euro coin to extract DNA Now all we need is a task the size of a pinhead or even a single cell nucleus. That tells you how much progress has been made!”
Identify relatives of a suspect
These immense advances have made it possible in particular to solve the case of Elodie Kulik, a young woman murdered in the Somme in 2002. Research into DNA kinship has truly changed the situation, as evidenced by her father, Jacky Kulik: “The investigation was long. From the start, we knew that we would certainly come to something given the fact that we had nuclear DNA. For Elodie, this is the first time that the DNA technique of parentage was used. Without this flash of genius, the DNA would have remained silent for years.”
A flash of genius that we owe to Emmanuel Pham Hoia, gendarmerie colonel and genetics expert: “On a scientific level, I realize that there is always this genetic profile which was found at the crime scene and suggests that it is that of the rapist of Elodie Kulik. There, I tell myself that you have to look for matches at only 50%: that is to say, try to find the father, mother or children of the suspect, if they are on file.
This search for kinship keeps its promises: the father of the suspect is identified, then allowing investigators to go back to the perpetrators of the crime.
Highly accurate composite portraits thanks to genetics
Another advancement in science: genetic robot portraits. DNA now makes it possible to achieve much more precise results and the technique has been authorized by the courts since 2014. A very useful method for investigators from the central office for the repression of violence against persons (OCRVP), who work on cases not elucidated. His boss, divisional commissioner Franck Dannerolle explains: “The robot portrait is one of the oldest tools used by the judicial police. In 2023, this tool is used differently. We now use DNA coding elements that are found on a trace of the scene of crime to succeed in extracting the characteristic elements of the morphology: the color of the eyes, the skin, the hair… It is a tool which will make it possible to direct the investigators.
Behavioral science also comes to the rescue of surveys and cold cases. For weeks, behavior analysts prepare the course of police custody. Then, behind their screen, they observe the suspect and guide the investigators in their questions. The technique was for example used last week in the case of the disappearance of Karine Esquivillon. Michel Pialle, her husband, ended up saying where the body was.
A game of chess
Four years ago, a profiler faced serial killer Jacques Rançon and his confession helped solve a thirty-year-old cold case. Marie-Laure Brunel-Dupin is now head of the unsolved cases division of the gendarmerie: “It’s literally a game of chess. And it’s the smartest one who wins. It’s not necessarily the one who knows the rules best, and it’s not the strongest who wins the game. It’s very satisfying when a team manages to get a serial killer to talk and confess a fact. But we are not having a party because he confessed, we are thinking of the victim and his family.”
Other techniques exist: the analysis of traces of blood on a crime scene or forensic medicine. They are to be discovered in the franceinfo podcast “cold case, science against crime”.