From this episode we know that Angel was connected with one of "the Families" and named after his father. I'm assuming the Families refers to the Mafia. There was a famous Mafia hitman named Frederick "The Angel" Tenuto. His last name and our Angel's are spelled differently, and there's a big time gap between the two, but I think it's too close to be a complete coincidence.

Tenuto escaped from the Philadelphia County Prison along with Willie Sutton in 1947. He spent 10 years on the FBI's Ten Most Wanted List, and is rumored to have died in the early 60s.