Disciplinary issues prompted the transfer of gangster James "Whitey" Bulger to the federal prison where he was beaten to death within hours of his arrival, a federal law enforcement official said Thursday.

An official briefed on the investigation told The Associated Press that the 89-year-old former Boston crime boss and longtime FBI informant was transferred to USP Hazelton in West Virginia after causing problems at the prison in Florida, where he had been serving a life sentence for participating in 11 killings.

The official insisted on anonymity because he was not authorized to release details. He said he did not have specifics on Bulger's behavior in Florida, and did not know why Bulger was specifically sent to Hazelton.

Bulger, who ran a largely Irish mob in Boston in the 1970s and '80s, ratted on his rivals, the New England Mob, to the FBI while simultaneously running his own crime ring responsible for loansharking, extortion and a string of murders.

Bulger fled Boston in late 1994 after being tipped off by his FBI handler that he was about to be indicted. He spent the next 16 years as one of America's most wanted fugitives until he was found in 2011, living with his girlfriend in a rent-controlled apartment in Santa Monica, California.

A Mafia hit man, Fotios "Freddy" Geas, who is said to hate "rats," and at least one other inmate are believed to have been involved in Bulger's killing , an ex-investigator briefed on the case said Wednesday. The longtime investigator was not authorized to discuss the matter and spoke on condition of anonymity.

Many questions remain about why Bulger was put into the general population at USP Hazelton when his notoriety as a crime boss and FBI informant was highly publicized.

The FBI has declined to comment on the investigation.

Federal officials have only said they are investigating Bulger's death as a homicide.

The federal Bureau of Prisons has not responded to requests for comment about safety concerns at USP Hazelton.

Robert Hood, a former warden at the federal supermax prison in Florence, Colorado, said Bulger's age alone would put him potentially at risk in the prison's general population. Add Bulger's notoriety, and Hood said he could not imagine housing him with other inmates.

"A known snitch in almost every prison is in jeopardy," Hood said. "I don't think it was intentional. I just think they gave too much credit to the age of the inmate, thinking: 'He's old, he's not going to hurt anyone,'" he said.

Bulger's killing marks the third at Hazelton in the last six months.

Last week, five members of Congress wrote to Attorney General Jeff Sessions about what they called "dangerous continual understaffing" at federal prisons in West Virginia and Pennsylvania and stated their alarm about the deaths at USP Hazelton.

Justice Department spokesman Wyn Hornbuckle said DOJ was "aware of the concerns raised in the letter" and would respond to the members of Congress.


Lavoie reported from Richmond, Virginia.