Salvatore "Sammy the Bull" Gravano (born March 12, 1945) is an American former mobster who rose to the position of underboss in the Gambino crime family of New York City before becoming a government witness. As the underboss, Gravano played a major role in prosecuting John Gotti, the crime family's boss, by agreeing to testify as a government witness against him and other mobsters in a deal. As part of the agreement, Gravano confessed to his involvement in at least 19 murders, although he was al...