The Justice Department and the FBI have been unable to locate any documents that support James “Whitey” Bulger’s claim that he was authorized to commit crimes, including murder, according to a government memorandum filed in court Friday.
Bulger, 83, says that former federal prosecutor Jeremiah T. O’Sullivan, who died in 2009, verbally promised him lifetime immunity decades ago, though he has yet to provide specifics, including the date he says it was granted.

Comments
Any reasonable person who studies what was done by Bulger must conclude that he had to have immunity and was protected by the Federal Government. He would never have been able to get away with the crime wave that was perpetrated by these men...
Even if such a document existed, it is impossible to imagine the FBI pulling it out of a filing cabinet on request.
Whitey is now facing a situation without much political protection (no more Billy actively pulling strings every day) or criminal muscle (who's risking their life for an 84-year old guy who will live out his time on earth behind bars?). Not to mention a secretive institution that wants to protect its tattered reputation and might well shade the truth to do it (the FBI).
I doubt there are good Las Vegas odds on his getting away with this one.