"Wherever you go you leave behind a trace of yourself, and take with you a trace of the place you’ve been."  That’s what crime lab cops know.

Of course, canvassing the crime scene, interviewing suspects, and following up leads is still the lifeblood of a police investigation.

Then there’s "clown forensics," creative investigative techniques that work only if the detective can keep a straight face.

For example, two detectives interrogate a suspect by putting a spaghetti strainer on his head as a "lie detector." He believes it works-so it does.

Another creative tactical deception I recently heard about is "neuron skin particle testing," used occasionally in a small town in the midwest.  The chief says he "needs leverage" to get suspects to confess, so he "invented" a lab test.  Early in the interview, the chief tells the suspect, "Humans lose about 10,000 particles of skin every day.  That’s where housedust comes from."  The chief shows the guy blowups of partial fingerprints, blood matching, DNA testing, and, of course, "neuron skin particle testing."

Most criminals get their legal education from television.  This suspect probably saw television shows about police science and he believes nearly anything is possible in the laboratory.

"Preliminary lab results indicate that you were in the room where the body was found," says the chief.  There are no lab results, but the guy doesn’t know that.  The suspect begins to sweat, thinking they’ve found his "skin particles."  He challenges the chief, asking how the test works.

"I’m sorry, sonny," says the chief, "it would be a violation to reveal the process outside the courtroom."

Most suspects roll over within an hour or two.  But what about innocent people?

The chief explains with a smile: "The test doesn’t affect innocent people.  If they weren’t at the crime scene, their skin particles wouldn’t be there."