How? By falling for the oldest trick in the book: The Ol' Chewing Gum Survey ruse.As first reported by the Kennebec Journal in Maine, an undercover officer with the Seattle Police Department got a DNA sample from Gary Sanford Raub by asking the homeless man to participate in the survey. Saliva from the gum was then used to match DNA found in the kitchen of a Maine murder victim, possibly bringing to a close a case that's been cold since 1976.
The Journal also reported the DNA was a match on a knife used in a stabbing in Seattle.
Which goes to show: If you like to get stabby with other people, don't participate in chewing gum surveys.