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. To learn more about the world of crime, forensic science and how to catch the bad guys, follow the links below. When we're first introduced to the character of Sherlock Holmes in "A Study in Scarlet," Sir Arthur Conan Doyle's first published story of the famous detective, we find him in the chemical laboratory of a hospital. From the very start we can see Holmes is a medical man, someone who trusts very strongly the power of scientific fact.
The stories of Doyle -- who attended the University of Edinburgh Medical School and ran his own medical practice before writing full time -- were a major influence on real life detective work and the art of criminal investigation. Edmond Locard himself was very familiar with the adventures of Sherlock Holmes, and he would even suggest his students read the mysteries for class.
Indeed, the philosophies of Doyle's character helped to form the core of Locard's principle. In the story "The Adventure of Black Peter," after a student reports a lack of footprints at a crime scene, Holmes responds: "As long as the criminal remains upon two legs so long must there be some indentation, some abrasion, some trifling displacement which can be detected by the scientific researcher" [source: University of Virginia Library ].
Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Prev NEXT. Physical Science. Forensic Science. A scientist at Preston Forensic Science Laboratory removes a hair from a hat left at the scene of a shooting. In the early 20th century, Dr. Trace evidence can be used to link people or objects to places, other people or other objects, and often serves as a starting point, or lead, for a particular line of investigation.
Trace evidence helps to put together pieces of the investigative puzzle—from which direction did the perpetrator arrive? How close was the victim to the window when the bullet shattered the glass? Were stolen goods transported in a particular vehicle? The answers to these questions can significantly impact the outcome of a trial and these answers may be found via careful examination of tiny bits of evidence. Important developments in trace evidence came alongside advances in microscopy, chemical analysis, and for evidence comparison purposes, database technology.
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