Yea Pistone never was privy to that info until Massino flipped and told who all was there. I'm not even sure the "real" story came out until he flipped and testified against Vito Rizzuto.

And Moe you could tell in the book that Pistone really thought a lot of Sonny Black and that Lefty really annoyed him. To me that just shows how good of a job he did while undercover to get their trust like that. I honestly think all Lefty seen was the money aspect of it and Sonny actually considered Donnie a friend.