James 'Whitey' Bulger was killed in his cell at U.S. Penitentiary Hazelton in West Virginia on October 30 (2018), and now his death certificate has been released.
Bulger's death is listed as a homicide.
TMZ sources claim four fellow inmates delivered the blows that killed the notorious mobster and also attempted to gouge his eyes out and cut out his tongue.
Prison officials believe the fatal attack on wheelchair-bound Bulger, 89, was linked to his decision to become an informant.
Bulger was among the FBI's most wanted criminals before he was captured in Santa Monica, California in 2011.
He was convicted in 2013 for his connection to at least 11 murders, among other crimes, and was serving a life sentence at the time of his death.