Joseph D. Pistone is a former undercover FBI agent known for his infiltration of the Mafia. He operated under the alias Donnie Brasco during the late 1970s and early 1980s, successfully gathering evidence against organized crime figures. His work led to over 100 convictions and significantly impacted the fight against the American Mafia. After his undercover operation, Pistone's life changed dramatically due to threats from the Mafia, prompting him to enter witness protection for his safety.