Oct. 30 (UPI) -- Notorious Boston mob boss James "Whitey" Bulger was found dead Tuesday one day after being transferred to a federal prison in West Virginia, federal officials said.
Unnamed sources told the Boston Globe that a fellow inmate with ties to the mafia killed Bulger. Federal investigators were probing the death.
"The U.S. Attorney's Office for the Northern District of West Virginia and the FBI will be conducting an investigation into the death of James Bulger. No other information will be released at this time," said Stacy Bishop, a spokeswoman for William J. Powell, the U.S. attorney for the Northern District of West Virginia.
Corrections officials relocated the 89-year-old from a temporary stay at a facility in Oklahoma to the high-security USP Hazelton in Bruceton Mills, W.Va., on Monday. Prior to Oklahoma, Bulger had been held at U.S. Penitentiary Coleman II in Sumterville, Fla.
Officials found Bulger unresponsive around 8:20 a.m.
"Life-saving measures were initiated immediately by responding staff. Mr. Bulger was subsequently pronounced dead by the Preston County Medical Examiner," the U.S. Bureau of Prisons said in a statement.
A jury convicted Bulger in 2013 on 31 criminal counts for his involvement in 11 murders across the country during his time as leader of the Boston-based Winter Hill Gang.
A federal judge sentenced him to two life-in-prison terms plus five years in November 2013 and ordered him to pay $19.5 million in restitution and forfeit $25.2 million to the government.
"The testimony of human suffering that you and your associates inflicted on others was at times antagonizing to hear and painful to watch," Judge Denise Casper said during the sentencing. "The scope, the callousness, the depravity of your crimes, are almost unfathomable."
The FBI had been searching for Bulger for 16 years before his arrest. The bureau added him to its "10 Most Wanted Fugitives" list in 1999, offering $250,000 for information leading to his arrest. The manhunt even expanded to Britain after a businessman reported spotting him near London's Piccadilly Circus.
Prosecutors believe Bulger was responsible for more crimes during the 1970s, 80s and 90s, while he oversaw his criminal empire, than he was convicted of.
A source told the Boston Globe that Bulger had been in deteriorating health for years and had a heart condition.