"This undated file booking photo, obtained by WBUR 90.9 - NPR Radio Boston, shows Boston mob boss James ""Whitey"" Bulger, who was captured on June 22, 2011, in Santa Monica, Calif., after 16 years on the lam. A judge is set to hear arguments on Bulger's claim that he was given immunity to commit crimes while he was an FBI informant. The 83-year-old Bulger is awaiting trial in a racketeering indictment accusing him of participating in 19 murders. He claims a federal prosecutor gave him immunity for his crimes while he was providing the FBI information on local leaders of the Mafia, his gang's main rivals. (AP Photo/WBUR 90.9, File)"