Joseph D. Pistone
Joseph Dominick Pistone, alias Donnie Brasco, (born September 17, 1939), is a former FBI agent who worked undercover for six years infiltrating the Bonanno crime family and to a lesser extent the Colombo crime family, two of the Five Families of the Mafia in New York City. Pistone was an FBI agent for 17 years and is considered to be an FBI legend.
Pistone was a pioneer for deep long-term undercover work. J. Edgar Hoover originally did not want FBI agents to work undercover because it could be a dirty job and might end up tainting the agents, but Pistone's work helped convince the FBI that using undercover agents instead of just using informants was a crucial tool in law enforcement.