I believe merlino referred to Sully Sullivan, a Boston gangster who was on the FBI top 10 most wanted list.

In the show, Sully lived with his girlfriend and his mother, while the word around town was that Sully died years ago. In the meantime, he had his people collect for him and whatnot.



But Ray Donovan's a TV show. As for the true story, I really have no idea.