In 2003, answers were proving hard to come by in the disappearance of four people in Colorado. It would take years to catch a killer who called himself 'Hannibal' and was a paid criminal informant for the FBI. “48 Hours" Correspondent Harold Dow reports. This classic "48 Hours" episode last aired on 8/20/2011. Watch all-new episodes of “48 Hours” on Saturdays, and stream on demand on Paramount+.