Collecting and Preserving Trace Evidence at a Crime Scene [Locard's Exchange Principle]

Dr Edmund Locard Image by blogtrotters via Flickr

Dr. Edmond Locard (1877–1966) 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.

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, and in 1918, developed 12 matching points for fingerprint identification. He continued with his research until his death in 1966.

In 1910 Locard succeeded in persuading the Lyons Police Department to give him two attic rooms and two assistants, to start what became the first police laboratory. He was a pioneer.

The young Georges Simenon, later to become a well-known detective writer, is known to have attended some Locard lectures in 1919 or 1920.

Locard’s Exchange Principle states that with contact between two items, there will always be an exchange. This is the basis of trace evidence collection at a crime scene.

Trace evidence is material found at a crime or accident scene in small (maybe almost invisible) but measurable amounts. Trace evidence is critically important as it can definitively link an individual or object to the crime or accident scene. [From Wikipedia, the free encyclopaedia].

Trace Evidence Can Help Solve the Case

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