Bulger was the head of the violent Winter Hill Gang in Boston in the 1970s and 80s. He lived a double life as a criminal and FBI informant — and used the arrangement to his advantage. In 1995, after an FBI agent warned Bulger of a planned indictment against him, Bulger fled and became a fugitive.
He was captured in 2011 in Santa Monica, CA and later convicted of 11 murders.
Bulger was sentenced to a life sentence and had until recently been serving his time in a Florida federal prison. He was recently transferred to Hazelton Penitentiary where his body was discovered on Tuesday. Emergency dispatchers reportedly response to a call of an inmate in cardiac arrest.
Initial reports of Bulger's death speculated that he had been murdered in prison by a person with mafia ties.
Bulger’s life and criminal exploits served as the inspiration for many books and films including The Departed and Black Mass — the latter starred Johnny Depp as the crime boss.
*This article has been updated to include the most recent information regarding the cause of Bulger's death. It is a developing story.