I've read on this site that Roy DeMeo and people he worked with were pretty violent.

Carlo claims that Richard Kulkinski was the most violent person involved in this sort of thing; but it's debatable if half of what he said or claimed to have done for certain people is really true. Philip Carlo's book that they made into a movie do not help as there's a lot of wrong information in it apparently.

It's sad what happened to writer Philip Carlo but his books on the subject of your question you asked are poorly researched and written; but he had terminal ALS at the time.