James "Whitey" Bulger, who lived a double life as one of Boston's most notorious mobsters and as a secret FBI informant before going on the run for 16 years, was killed at a federal prison in West Virginia, sources said Tuesday.
The FBI was looking into Bulger's death and a prison employee briefed on the matter said it was being investigated as a homicide. A U.S. Bureau of Prisons statement had earlier confirmed Bulger had died and said the FBI was investigating.
Bulger, who was 89, had been transferred a day earlier to the high-security prison in a wheelchair, the prison employee said.