Posted Aug 29, 2012 04:49 pm CDT
If New York City police want to collect a DNA sample from a suspect who takes a drink or smokes a cigarette in the interrogation room, they had better be careful—and clean.
Police protocols outline the procedures designed to prevent contamination, the New York Times reports. Surfaces within reach of the suspect need to be cleaned with a solution consisting of a 10-to-1 ratio of water to bleach. Containers such as cigarette packages and chewing gum containers should be unopened. Ashtrays should be unused, clean and disposable. And, in a nod to chain-of-evidence concerns, detectives should maintain “unbroken eye contact” with the sample until it is collected.
The Times spoke with Warren Leight, an executive producer for Law & Order: Special Victims Unit, about the detailed requirements. “I don’t think we’ve ever written a scene that way,” he said.