The FBI’s dark side exposed

For more than 20 years, FBI headquarters in Washington knew that its Boston agents were using hit men and mob leaders as informants and shielding them from prosecution for serious crimes including murder. Until now, the still-unravelling Boston FBI scandal has been portrayed largely as the work of a handful of local agents — mavericks willing to deal with the devil to bring down a Mafia family. But documents have been obtained that directly connect FBI headquarters to a pattern of collusion with notorious killers