Scientist Special: Edmond Locard

“Any action of an individual, and obviously the violent action constituting a crime, cannot occur without leaving a trace” – Edmond Locard

It seems apt to kick off Locard’s Lab with a brief post about the man behind the name – Edmond Locard. Every forensic scientist and his dog have heard the statement “every contact leaves a trace”, and Locard is the scientist responsible for coining the phrase.


Born in 1877, a young Edmond Locard began his career by studying medicine in Lyon, France. He soon developed a particular interest in the application of science to law, producing a thesis entitled “Legal Medicine under the Great King”. Not only did he excel in the field of medicine, but he also later went on to study law and successfully passed the bar exam. Locard worked under medico-legal expert Alexandre Lacassagne, the gentleman famous for essentially fathering the field of criminology. His links with famous forensic experts did not end here, as he later studied alongside anthropologist Alphonse Bertillon, known for his work with anthropometrics. In 1910 Locard moved on to found the world’s first police laboratory in the attic of a courthouse, in which legal evidence could be collected and analysed. It took two years for Lyon police to actually recognise the laboratory.

Locard’s famous phase, “every contact leaves a trace”, became known as Locard’s exchange principle. The theory states that when two objects come into contact, each will leave some trace on the other. This exchange theoretically means that there will always be some evidence of the perpetrator at a crime scene to provide investigators with a link (of course this is simpler in theory than in practice). Perhaps his most famed publication was Traité de Criminalistique, or Treaty of Criminalistics, a vast seven-piece volume that detailed forensic techniques and ideas that are still used today.

In true dedication to his work, Locard continued his research right up until his death in 1966.



Chisum, W.J. Turvey, B. E (2011). Crime Reconstruction. California: Elsevier Inc.

Erzinclioglu, Z (2004). The Illustrated Guide to Forensics – True Crime Scene Investigations. London: Carlton Pub. Co.

Stauffer, E. 2005. Dr Edmond Locard and Trace Evidence Analysis in Criminalistics in the Early 1900s: How Forensic Sciences Revolve Around Trace Evidence. [Online] [Accessed 18 November 2014] Available from: