Dr. Edmond Locard was a pioneer in forensic science who became known as the Sherlock Holmes of France. He formulated the basic principle of forensic science: “Every contact leaves a trace”. This became known as Locard’s exchange principle. Born on November 13 1877 in Saint-Chamond, France, Locard studied medicine and law at Lyon, eventually becoming the assistant of Alexandre Lacassagne, a criminologist and professor. He held this post until 1910, when he began the foundation of his criminal laboratory. He produced a monumental, seven-volume work, Traité de Criminalistique.
Locard worked as a medical examiner during World War I and was able to identify causes and locations of death by looking at stains or dirt left on soldier’s uniforms.In 1910, Locard succeeded in persuading the Police Department of Lyon (France) to give him two attic rooms and two assistants, to start what became the first police laboratory. He was a pioneer. Locard believed that no matter where a criminal goes or what a criminal does, he will leave something at the scene of the crime. At the same time, he will also take something back with him. A criminal can leave all sorts of evidence, including fingerprints, footprints, hair, skin, blood, bodily fluids, pieces of clothing and more. Dr. Locard tested out this principle during many of his investigations. In 1912, for instance, a Frenchwoman named Marie Latelle was found dead in her parents’ home. Her boyfriend at the time, Emile Gourbin, was questioned by police, but he claimed he had been playing cards with some friends the night of the murder. After the friends were questioned, Gourbin appeared to be telling the truth. When Locard looked at the corpse, however, he was led to believe otherwise. He first examined Latelle’s body and found clear evidence that she was strangled to death. He then scraped underneath Gourbin’s fingernails for skin cell samples and later viewed the results underneath a microscope.
Very soon, Locard noticed a pink dust among the samples, which he figured to be ladies makeup. Although makeup was popular around the time of the murder, it was by no means mass produced, and this was reason enough for Locard to search a little further. He eventually located a chemist who developed a custom powder for Latelle, and a match was made. Gourbin confessed the murder, he had tricked his friends into believing his alibi by setting the clock in the game room ahead. Locard’s exchange principle had worked. Locards theory is still used today, When a crime is committed, fragmentary (or trace) evidence needs to be collected from the scene.
A team of specialized police technicians go to the scene of the crime and seal it off. They both record video and take photographs of the crime scene, victim (if there is one) and items of evidence. If necessary, they undertake a firearms and ballistics examination. They check for shoe and tire mark impressions, examine any vehicles and check for fingerprints.