A major break in the Long Island Serial Killer case. The 18-month search for a missing New Jersey woman finally came to an end this week when police on Long Island, New York, announced the discovery remains believed to be 23-year-old Shannan Gilbert. On Saturday, Dec. 17, 2011, the remains were positively identified as Gilbert. As "48 Hours Mystery" correspondent Erin Moriarty reports, the search for Gilbert uncovered a greater mystery.Erin Moriarty has the latest developments.