<P> In forensic science , Locard 's exchange principle holds that the perpetrator of a crime will bring something into the crime scene and leave with something from it , and that both can be used as forensic evidence . Dr. Edmond Locard ( 13 December 1877 -- 4 May 1966 ) was a pioneer in forensic science who became known as the Sherlock Holmes of France . He formulated the basic principle of forensic science as : `` Every contact leaves a trace '' . Paul L. Kirk expressed the principle as follows : </P>
who stated that there is an exchange of materials when two objects come into contact with each other
Dr. Edmond Locard