Frank Calabrese Sr.

Former mobster and FBI informant

Frank Calabrese Sr. is a former American mobster and FBI informant. He was a high-ranking member of the Chicago Outfit and was involved in various crimes, including extortion and murder. Calabrese Sr. became an informant for the FBI in the 1990s and provided information on the mob's activities. He has written a memoir about his life and has appeared on various TV shows.