In 1965, James J. "Whitey" Bulger was released from Federal prison after serving a nine-year sentence for robbing banks. After a few years of working as a janitor, he became an enforcer for South Boston mob boss Donald Killeen. After Killeen was murdered by an enforcer for the Mullen Gang, Winter Hill Gang boss Howie Winter mediated the dispute between Bulger and the remaining Killeens and the Mullens, who were led by Patrick Nee. Winter soon chose Bulger as his man in South Boston. Shortly afterward, Bulger became partners with Flemmi.