Jeremiah O'Sullivan (lawyer)

Jeremiah T. O'Sullivan (died February 10, 2009) was a Boston-based federal prosecutor for the United States Department of Justice. In 2012, he was identified as the federal agent who, it is believed, provided immunity to Winter Hill Gang leader James "Whitey" Bulger. Bulger was accused of racketeering and being involved in nineteen murders. O'Sullivan was a lawyer in the 1970s and 1980s, prior to becoming the head of the New England Organized Crime Strike Force. In 1970, he was the Deputy Assistant Attorney-General for the Commonwealth of Massachusetts.

In February 1979, federal prosecutors indicted numerous members of the Winter Hill Gang, including boss Howie Winter, for fixing horse races. Bulger and his right-hand man Steve Flemmi were originally going to be part of this indictment, but Federal Bureau of Investigation (FBI) agent John Connolly and his supervisor John Morris were able to persuade O'Sullivan to drop the charges against them at the last minute. Bulger and Flemmi were instead named as unindicted co-conspirators. In 2009, Connolly was sentenced to forty years in prison for second-degree murder. Morris was granted immunity in exchange for a testimony against Connolly.

In 1998, O'Sullivan suffered a heart attack and several strokes after being asked to testify about Bulger and Flemmi. He remained in a coma for a month. Five years later, O'Sullivan spoke in front of Congress during the Committee on Government Reform's investigation of the FBI's Boston branch. He stated that he knew some informants were committing murder and that they had relationships with FBI, but O'Sullivan said he did not act upon the situation because he was "intimidated by the bureau". O'Sullivan denied having personally provided protection to Bulger and his associates.

In the 2015 movie Black Mass, O'Sullivan was portrayed by Lewis D. Wheeler.

Personal life
O'Sullivan was married to Karen (née Hoke).

Death
O'Sullivan died in 2009, aged 66.