A notorious Mafia hitman his died while in prison.
Joseph "Mad Dog" Sullivan has passed away from cancer at the age of 78.
A career criminal, Sullivan was serving three life sentences and is best known for being the only man to escape Attica Prison.
The hitman is believed to have killed between 20 and 30 people on behalf of the Mob.
Sullivan was once hired to kill John Fiorino -- a Teamsters Union official and reported mobster, shooting him down outside a Rochester, New York restaurant in 1981.
- Jagajeet Chiba, Gambling911.com