Dateline NBC

Crossing the Line (2009) (17x59)

Air date: Jul 10, 2009

Two childhood friends from South Boston take divergent paths: John Connolly was one of Boston's most celebrated FBI agents, and James "Whitey" Bulger became a notorious mobster. Connolly makes a deal with his old friend Bulger: Become an FBI informant, and his illegal gambling operation can continue without interference from the law. NBC’s Dennis Murphy reports on the story that became the basis for “The Departed.” Watch the full show here.