In the season premiere of "48 Hours Post Mortem," correspondents Anne-Marie Green and Peter Van Sant discuss the brilliant undercover operation that used chewing gum to catch a killer in two cold cases. They reveal how Detective Susan Logothetti and her colleagues developed the ruse, what it was like to confront the murderer, Mitchell Gaff, and why he spent over two decades in a treatment center for sexually violent predators.
26m ago (26:19)