The film is based on Joe Pistone's book, Donnie Brasco: My Undercover Life in the Mafia.
You can watch Joe Pistone discuss his undercover life on a Current TV segment and hear actual recordings of Pistone's conversations with Lefty Ruggiero via the below link:
I met Joseph Pistone when he visited Philadelphia a few years back and I later interviewed him.
You can visit an earlier post and see photos of of the legendary FBI Special Agent as well as the real mob guys. You can also read my column about Joe Pistone and my review of Pistone's book The Way of the Wiseguy in the Philadelphia Inquirer, via the below link: