Halloran was gunned down on May 11, 1982, alongside fellow Irish mob figure Mike Donahue, outside a bar and grill resting off the South Boston waterfront. Per federal court filings, Halloran was cooperating or trying to cooperate with the FBI related to his knowledge of several Irish mob murders.

Donahue and Halloran were part of the notorious Winter Hill Gang, otherwise referred to as Boston’s Irish mob.

It was May 1982, and Michael Donahue had ducked into a bar on Northern Avenue for a quick pop, and when he came out to get into his car he was with Brian Halloran, a guy he knew from the neighborhood in Dorchester. Michael Donahue was a truck driver, a Teamster, with a wife and three kids. Brian Halloran was a criminal who had tried to turn in Whitey Bulger, the South Boston gangster, and as a result was a dead man walking.

Halloran asked Michael Donahue for a ride, figuring that if he had a guy like Donahue beside him, he'd live another day. But the myth that wiseguys kill only each other died with Michael Donahue in a hail of machine-gun fire on Northern Avenue. Halloran's killers, including Whitey Bulger, fired indiscriminately into the car.

Tommy Donahue was just a kid, so nobody had the heart to tell him how his father had died. All he knew was that he missed his dad.

"My father went to all my baseball games," he said. "I'd be standing there in the outfield, looking around for him. Then it would dawn on me that he was gone and he wasn't coming back, and it would just crush me."