Secondary DNA Transfer: The Rarely Discussed Phenomenon That Can Place the Innocent (and the Dead) at a Crime Scene They’ve Never Been To – Criminal Legal News

In 1930, the French scientist Edmond Locard published a journal article in which he laid the groundwork for what would become the field of forensic science. Locard said a criminal actor will always leave traces of his or her presence at a crime scene and will always leave with traces of the scene on his or her person. Locard’s Exchange Principle revolutionized police investigative techniques.

The discovery of DNA further transformed the field of forensics. DNA exists in every person at the molecular level and is highly particularized to an individual. As such, DNA evidence has become the gold standard for forensic identification in criminal cases. When a suspect’s DNA is found at a crime scene, investigators have strong, virtually unassailable proof that the suspect was there.

Or do they?

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