One of the men charged in the killing of James “Whitey” Bulger inside a West Virginia prison said in an exclusive jailhouse interview that all the inmates in his unit knew in advance that the notorious gangster was being moved there.

Bulger, 89, was found beaten to death less than 12 hours after he was placed in his cell at the USP Hazelton federal prison, one of the most violent penitentiaries in the country.

“Everybody knew he was coming,” Sean McKinnon told NBC News in a phone call from a Florida jail.

McKinnon, 36, is accused of acting as a lookout while two other inmates rushed into Bulger’s cell and beat him with a lock on the morning of Oct. 30, 2018.

At a detention hearing last month, prosecutors said McKinnon told his mother in a recorded phone call before Bulger was moved to the prison that the Boston mobster was set to arrive there, suggesting he had inside information that played a role in the killing.

McKinnon told NBC News that Bulger’s impending arrival at USP Hazelton was an open secret in his housing unit.

“I heard it from another inmate — not even one of the guys from Massachusetts,” he said. “It wasn’t like I got this secret news. I was just a little fish in the sea.”

The federal Bureau of Prisons has received sharp criticism for its decision to place Bulger in the general population of a penitentiary where two inmates had been killed in the previous six months. It remains unclear why an inmate like Bulger, an elderly, former FBI informant, was moved to a prison like USP Hazelton.

“What did they think was going to happen?”

said Jack Donson, a retired Bureau of Prisons official who spent most of his 23 years at the agency screening inmates set to enter the federal prison in Otisville, New York. “There was a breakdown at every level.”

A spokesman for the Bureau of Prisons declined comment.

Prosecutors say two men, Fotios “Freddy” Geas, 55, and Paul J. DeCologero, 48, killed Bulger minutes after all the cell doors on their unit were unlocked ahead of breakfast.

Geas and DeCologero were both involved in organized crime in Massachusetts. Geas, a mafia hitman, was serving a life sentence for murder. DeCologero was serving a 25-year sentence after being convicted of racketeering and witness-tampering.

McKinnon was from New Hampshire and had no known affiliation with organized crime, according to local authorities. He was in prison for stealing guns from a firearms store and selling them in exchange for drugs, and he was locked up in the same cell as Geas.

Once the unit's doors opened at 6 a.m., DeCologero went into the cell shared by Geas and McKinnon, according to prosecutors. The three men walked out a few minutes later, with Geas and DeCologero heading straight into Bulger’s cell. It took them only seven minutes to murder the once-feared crime boss and leave his cell, prosecutors said.

During that time, McKinnon was sitting at a table that provided him a view of Bulger’s cell and the guard station, according to prosecutors.

In his interview with NBC News, McKinnon said he was in fact sitting among a group of other inmates watching television.

“There were 10 other guys there with me,” he said.