a) they had the perp’s DNA (from a rape or murder IIRC)
b) they had a suspect who they thought might match the DNA
c) the cop followed the suspect and grabbed his littered cigarette butt
d) they matched the cigarette butt DNA to the crime scene DNA.
I guess if a bank robber smoked a cigarette and left the butt behind it might well be used as well; but it would only “work” if the guy's DNA was already in the system, otherwise all you have is DNA with no identity to match it to.
What scenario are you envisioning whereby a non violent criminal gets identified by DNA? They find his DNA where exactly? What type of crime scene?
Or one of his family members, didn't we just go over this????
What scenario are you envisioning whereby a non violent criminal gets identified by DNA? They find his DNA where exactly? What type of crime scene?
I watched an episode of CSI NY, that covered this nearly exact situation, the one with Gary Sinise...his employee used to run in a tough NY neighborhood, and he turned out OK but his brother didn't. His brother was involved in burying a body in a stadium several years ago. But they found DNA off a cigarette butt that put the CSI agent (good brother) at the scene. Turns out that at the time the bad brother was trying to quit smoking and took the partially finished butt from his brother for later, put it behind his ear, forgot about it and it fell out while he was burying the body.
The implication being the good brother was the culprit.
Luckily, it was in the script that the error was found, otherwise the innocent borther might spend the rest of his days behind bars.
I truly wonder how many DNA cases have resulted in error, as opposed to rectifying errors.