Locard

Edmon Locard (1877–1966) was a French criminologist and physician who is widely regarded as the founder of modern forensic science. He is best known for Locard's exchange principle, which holds that every contact between two objects results in a transfer of material and that evidence is exchanged between a person and their environment during the commission of a crime.

In 1910 Locard established the first dedicated forensic laboratory in Lyon, introducing a formal, scientific approach to the investigation of crimes. Under his leadership, the laboratory advanced methods for collecting, preserving, and analyzing trace evidence, including hair, fibers, powders, and other materials, and he emphasized careful documentation and the chain of custody as essential components of investigation.

Locard's work contributed to the professionalization of police science and crime scene investigation in France and influenced international practice. He trained numerous investigators and promoted standardized procedures, laboratory analysis, and the integration of multiple disciplines—medicine, chemistry, and microscopy—in criminal investigations.

Locard's legacy rests on the principle that evidence is transferred during contact and on the enduring emphasis on rigorous, methodical techniques in forensic science. His ideas helped shape modern crime scene processing, laboratory methods, and the broader development of forensic disciplines worldwide.