In this Sept. 17, 2008 file photo, John Martorano is questioned about his plea agreement in exchange for testifying against former FBI agent John Connolly, in the Miami Courthouse. Connolly is accused of helping the Boston mob murder Miami gambling executive John Callahan in 1982, at Miami International Airport. Martorano, who served 12 years in prison after a plea deal, and who has admitted killing 20 people, is expected to testify at the trial of James "Whitey" Bulger, Monday, June 17, 2013 in federal court in Boston. (AP Photo/Marice Cohn Band, Pool, File)
BOSTON (AP) — A former hitman who admitted killing 20 people has taken the witness stand at the racketeering trial of James "Whitey" Bulger.
John Martorano served 12 years in prison after striking a cooperation deal with prosecutors. He was released in 2007.
Bulger, the former leader of the Winter Hill Gang, is charged in a 32-count indictment that accuses him of participating in 19 murders in the 1970s and '80s. He is also charged with extorting bookmakers, drug dealers and others running illegal businesses.
Martorano is one of three former Bulger loyalists who struck deals with prosecutors and agreed to testify against him.
Bulger's former partner, Stephen "The Rifleman" Flemmi, and former Bulger lieutenant Kevin Weeks also are expected to be key prosecution witnesses.
Copyright 2013 The Associated Press.