"Donnie Shacks' main activity was murder. No question about it. That was his main function for the Colombo family and for organized crime in general. He was one of the top hit men in the New York area," said Joe Coffey, a former NYPD investigator.
With a litlle research, bet you'd find he had a close association with WJC too. A few names come to mind of people that met untimely deaths.