Gotti's underboss, Salvatore "Sammy the Bull" Gravano, aided the FBI in finally convicting Gotti. In 1991, Gravano agreed to turn state's evidence and testify for the prosecution against Gotti after hearing the boss making several disparaging remarks about Gravano on a wiretap that implicated them both in several murders. In 1992, Gotti was convicted of five murders, conspiracy to commit murder, racketeering, obstruction of justice, tax evasion, illegal gambling, extortion, and loansharking. He was sentenced to life in prison without parole and was transferred to United States Penitentiary, Marion in southern Illinois. While in prison, Gotti died of throat cancer on June 10, 2002, at the United States Medical Center for Federal Prisoners in Springfield, Missouri. According to former Lucchese crime family boss Anthony "Gaspipe" Casso, "What John Gotti did was the beginning of the end of "Cosa Nostra"".