the theories of Dr. E. Locarde, a pioneer French criminalist who states, “Every criminal leaves something of himself at the scene of a crime—something, no matter how minute—and always takes something of the scene away with him.” Every good detective knows this. This is why they search so intensely at a crime scene for that small part of the perpetrator that he has left behind: a hair, a drop of blood, a thread, a button, a finger or palm print, a footprint, traces of semen, tool marks, or shell casings. And, in most instances, they find it.
