Sammy Gravano

Salvatore “Sammy the Bull” Gravano is an American former Gambino crime-family underboss who became a government witness and testified against boss John Gotti.

John Gotti: John Gotti was an American mobster who led the Gambino crime family from 1985 until his imprisonment. Gravano served as Gotti’s underboss before cooperating with prosecutors against him.
Plea bargain: A plea bargain is an agreement in which a defendant pleads guilty in exchange for concessions from prosecutors. Gravano’s cooperation agreement exchanged testimony for a reduced sentence.
United States v. Gotti: United States v. Gotti was the 1992 federal racketeering case that convicted John Gotti and Frank Locascio. Gravano’s testimony supplied direct evidence that helped secure the convictions.
Joseph Valachi: Joseph Valachi was a Genovese crime-family member whose 1963 testimony publicly described the American Mafia. Valachi revealed Mafia structure publicly, while Gravano provided trial testimony against a sitting boss.
Paul Castellano: Paul Castellano was an American mob boss who led the Gambino crime family from 1976 until his murder in 1985. Gravano joined the faction that helped Gotti overthrow Castellano’s leadership.
Witness immunity: Witness immunity is legal protection that limits whether testimony can be used to prosecute the witness. Immunity rules shaped the risks and terms of Gravano’s cooperation.
Gambino crime family: The Gambino crime family is an Italian-American Mafia organization based in New York City. Gravano’s cooperation exposed the inner workings of the family he had helped lead.
Henry Hill: Henry Hill was a Lucchese crime-family associate who became a federal informant and entered witness protection. Hill’s informant story contrasts with Gravano’s high-ranking position in a rival family.
Joseph Armone: Joseph Armone was a Gambino crime-family captain and underboss under John Gotti. Armone’s later role as underboss followed Gravano’s rise within Gotti’s organization.
RICO: The Racketeer Influenced and Corrupt Organizations Act is a U.S. law targeting patterns of organized criminal activity. Federal prosecutors used RICO charges to pursue Gotti and other Gambino members.

Linked from 4 pages

Joseph MassinoRelated: Gravano’s earlier cooperation provides a precedent, though Massino was the first New York boss to testify.