Notorious Boston mobster Whitey Bulger was killed in a West Virginia prison Tuesday, sources told WBZ-TV I-Team chief correspondent Cheryl Fiandaca. He was 89 years old.

Bulger had just been moved to USP Hazelton, a high-security prison with an adjacent minimum security satellite camp in Bruceton Mills.

In a statement Tuesday afternoon, the prison would only say Bulger was “found unresponsive” at 8:20 a.m. and that “life-saving measures were initiated immediately by responding staff.” He was pronounced dead by the local medical examiner.

“The Federal Bureau of Investigation was notified and an investigation has been initiated. No staff or other inmates were injured, and at no time was the public in danger,” the statement read.

According to the Boston Globe, a “fellow inmate with Mafia ties” was being investigated for Bulger’s death.