One of four prisoners living in solitary confinement since the the 2018 jailhouse murder of infamous Boston mob boss James “Whitey” Bulger told NBC News he had nothing to do with Bulger’s killing and doesn’t understand why he’s still in the hole.

Sean McKinnon, who is nearly seven years into an eight-year federal prison term for robbing a Vermont gun store, had been cellmates at USP Hazelton in West Virginia with Fotios “Freddy” Geas, a mafia hitman and fellow inmate named as one of two suspects in Bulger’s killing. A fourth inmate at Hazelton, Felix Wilson, was also placed in solitary after Bulger, 89, was bludgeoned to death with a padlock inside a sock. Wilson had spent the previous night in the same cell with Bulger.

“I told the feds, ‘If I had something to tell them, I would,’” McKinnon, 35, told NBC News in a phone call from prison. “I know nothing. I’m an innocent man.”