A suspect in the brutal murder of notorious mob boss James “Whitey” Bulger had a longtime vendetta against informants, according to a private investigator, offering a possible motive for the crime. Bulger was beaten to death Tuesday at the Hazleton federal penitentiary in Bruceton Mills, West Virginia, when he was assaulted within hours of his arrival. One suspect, Fotios “Freddy” Geas, is a Mafia hitman serving a life sentence. “Freddy hated rats,” private investigator Ted McDonough told the Boston Globe. “Freddy hated guys who abused women. Whitey was a rat who killed women. It’s probably that simple.” Bulger was a longtime informant for the FBI. People familiar with the investigation have indicated Bulger was killed by more than one inmate, and that Geas didn’t deny his role in the attack. Geas is serving life—without the possibility of parole—for his role in the assassination of Adolfo “Big Al” Bruno, the former Mafia boss in Springfield, Massachusetts.