It was years and years ago, but I watched two documentaries on that guy, that had interviews with him in prison, very matter of factly telling the story of his life.
I don't recall the details, but I recall he definitely had an interesting enough life to base a movie on, lol.
edit: I remember him telling the story of how some mafia guys had heard of how he was totally fearless, and recruited him on that basis. He didn't grow up connected to the mafia, they had just heard about some stuff he had done to some guys who had messed with him or something, and said they needed guys like him.
Also, his nickname came from his technique of disposing bodies, which gave the fbi a lot of trouble identifying the time of death, basically made it impossible, he'd freeze the bodies and store them for a while and stuff, can't recall exactly.