In 1910, the Lyon police offered criminologist Edmond Locard the opportunity to form the first police laboratory. He was given two assistants and two small, unused attic rooms, where evidence collected from crime scenes could be scientifically examined.
By 1912, these two rooms became the world’s first forensic science laboratory when the Lyon police department officially recognized it and allowed the lab to be used in criminal investigations. It was from within these walls, Locard went on to solve some of the most high-profile criminal cases not only in France, but across the world.
Forensic-science pioneer Edmond Locard, center of the front row, and his team at the Lyon crime laboratory around 1930. Credit: Lyon municipal archives
Edmond Locard was born in 1877 in Saint-Chamond, France. He studied medicine and law at Lyon eventually becoming the assistant of Alexandre Lacassagne, a criminologist and professor. Under Lacassagne’s mentorship, Locard recognized the importance of applying scientific methods to criminal investigations. He developed a conviction that crime scenes themselves held objective evidence, waiting to be interpreted scientifically.
In 1910, Locard persuaded the Lyon police to allow him a modest workspace in the attic of the Lyon courthouse. With minimal funding and little institutional support, he established what is widely regarded as the world’s first police crime laboratory.
The lab began with two assistants and rudimentary equipment, but Locard compensated with ingenuity. He analysed materials most investigators considered worthless, such as dust, soil, fibres, handwriting, ink, and fingerprints. His approach contrasted sharply with prevailing methods, which favoured dramatic clues over microscopic ones.
Edmond Locard in his laboratory. Credit: Lyon municipal archives
During World War I, Locard’s expertise found a practical application. As a medical examiner for the French Secret Service, he meticulously analysed stains and damage on soldiers’ uniforms to deduce the causes and locations of their deaths. This experience sharpened his forensic skills and solidified his belief in the value of scientific evidence in solving criminal mysteries.
Locard distilled his philosophy into a principle that is now taught in every forensic science course: “Every contact leaves a trace.”
The idea rests on a fundamental physical truth that materials are constantly shedding and transferring. When a burglar breaks into a house, he leaves behind fibres from his clothing, skin cells, hair, or soil from his shoes. At the same time, he picks up particles from the scene, such as dust, glass fragments, wood splinters, or paint.
Later, Paul L. Kirk, a forensic scientist, expanded on Locard’s insight with the famous formulation: “…physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.”
Kirk emphasizes that evidence will always be there, although it might not always be obvious or easy to interpret. Instead, he argued that absence of evidence often reflected failure to search properly, not the absence of transfer.
Edmond Locard and his team, in the attic of the Lyon courthouse, busy with their analyses. Credit: Lyon municipal archives
One of the earliest cases in which Edmond Locard demonstrated the power of his exchange principle was the murder of Marie Latelle, a young woman found brutally strangled in her parents’ home. Suspicion soon fell on her fiancé, Emile Gourbin, a bank clerk known for his jealous and possessive nature. Yet Gourbin had a seemingly unbreakable alibi, supported by his friends who testified that he was playing cards with them at the time of the murder.
The physical evidence on Marie Latelle’s body was consistent with a violent struggle and strangulation. Scratches on her neck suggested that she had fought back desperately, clawing at her attacker as she was being strangled. Locard reasoned that if Marie had scratched her assailant, then traces of that struggle should remain beneath the attacker’s fingernails.
Locard meticulously scraped underneath Gourbin’s fingernails and examined the residue under a microscope. Among the skin cells, he found a fine pink dust.
Locard identified the pink dust as a cosmetic face powder. In 1912, such cosmetics were not mass-produced. Affluent women often commissioned bespoke blends from local chemists, each with a distinctive composition. Locard analysed the powder in detail and identified its ingredients: rice starch, zinc oxide, bismuth, magnesium stearate, and a reddish iron-oxide pigment known as Venetian red.
Armed with this chemical profile, Locard visited the druggists of Lyon until he found the one who had prepared this precise formula for Mademoiselle Marie Latelle. Confronted with this microscopic evidence of physical contact, Gourbin confessed. He admitted to setting the clock in the card room ahead of time, deceiving his companions into believing it was 1 a.m. when it was in fact only midnight. The ruse gave him the opportunity to slip away unnoticed, confront Marie, and commit the murder.
A plaque marking the building where Locard established his laboratory. Credit: Wikimedia Commons
Emile Gourbin’s conviction marked a watershed moment in the history of forensic science. It was among the earliest murder cases in which a verdict rested on the analysis of microscopic trace evidence. The outcome vindicated Locard’s approach and showed a once-sceptical world that scientific examination could uncover truth more reliably than alibis or even eyewitness testimony.
Today, Locard’s Exchange Principle underpins modern forensic techniques, from DNA analysis to gunshot residue testing. While the tools have grown vastly more sophisticated, the underlying logic remains unchanged.
Dr. Edmond Locard—who would come to be known as the “Sherlock Holmes of France”— retired as the head of the Lyon police laboratory, at the age of 73. He died in 1966 in Caluire. He oversaw over ten thousand criminal cases.
References:
# Edmond Locard: The Forensic Pioneer Who Revolutionized Crime Scene Investigation. Simply Forensic
# Edmond Locard – A Forensic Science Pioneer. Forensic's blog
# Inspiré par Sherlock Holmes, ce Lyonnais a révolutionné la police. ActuLyon
Comments
Post a Comment