Just watched a few episodes of this series. In episode 4, they show Nevada Gaming Testimony of Frank Sinatra. He sort of "rats" on Sam Giancana (granted this is long after Sam's untimely demise) but I've never heard him taddle like that.

Then he goes on to say, "Don't mention my name with Jimmy Fratianno. He's a perjurer!" This was after Jimmy turned state's evidence.