BOSTON -- James "Whitey" Bulger, the notorious Boston gangster who eluded authorities for nearly two decades before being caught in 2011, was found dead in prison Tuesday, officials said.

His death is being investigated as a homicide, said Justin Tarovisky, executive vice-president of the American Federation of Government Employees Local 420, which represents corrections officers at the West Virginia prison where Bulger had recently been moved.

Bulger, 89, was serving a life sentence after being convicted in 2013 of participating in 11 murders. He served as an FBI informant who ratted on his gang's main rival before becoming the agency's most wanted fugitives for 16 years until his arrest in Santa Monica, California.