Black Mass

The True Story of an Unholy Alliance Between the FBI and the Irish Mob, by Dick Lehr and Gerard O'Neill.

Though heavily involved in extortion, intimidation, assassination, and drug trafficking, Connolly's "good bad guy" did not receive so much as a traffic infraction for over 20 years. In time, however, the deal changed, and information began flowing the other direction, with Bulger manipulating Connolly and a small group of corrupt FBI agents to further his nefarious network. The criminals and the lawmen eventually became virtually indistinguishable.