John J. Connolly Jr.
Connolly (left, in 2008, and right in 2002) grew up in a South Boston housing project a few doors down from the Bulger family. As an FBI agent, Connolly persuaded James "Whitey" Bulger to sign on as an informant. With the help of tips from Bulger and Stephen Flemmi, the FBI began dismantling the Irish mob's chief rivals, the Italian Mafia. Connolly was convicted of second-degree murder in 2008, for leaking information that led to the murder of John Callahan in Florida. In March 2011, Connolly lost his appeal
to have that conviction overturned.