The FBI’s arrest of Boston crime boss James “Whitey” Bulger ended a 16-year-old hunt for a notorious career criminal who was immortalized by the Martin Scorsese film The Departed, loosely based on his story. But it should also remind us of one of Republican presidential candidate Mitt Romney’s finest hours.

Bulger was part of an extraordinary Irish-American immigrant family who represented the best and worst of the American experience. While Whitey became the head of the Irish mafia in Boston, his younger brother William went to college and became a lawyer before going into politics. Billy Bulger spent 35 years in the Massachusetts legislature, including 18 as the powerful president of the State Senate. In 1996, he was appointed president of the University of Massachusetts system, a position of enormous prestige and power.

It speaks volumes about the nature of Boston’s political life in that era that the brother of a crime boss could rise to the top of the state’s political system. Cynics could be forgiven for wondering whether Billy’s success was linked to Whitey’s activities, even though the politician publicly pretended not to know what his beloved big brother did for a living. But it’s just as possible Billy’s political power also helped Whitey and his Winter Hill Gang.

But the pretense Billy knew nothing about Whitey’s crimes was exploded once his brother went on the lam in 1995. After years of exploiting his role as an FBI mob informant that enabled him to both knock off criminal rivals and evade prosecution, Whitey was indicted. But, thanks to his FBI informant, he escaped capture. His brother, who was still the president of the Massachusetts State Senate, may have aided the escape of the man wanted in connection with 19 murders as well as drug trafficking. What we do know for sure is Billy spoke with his fugitive brother via elaborate procedures designed to evade police detection and made no effort to help the authorities bring him to justice. In 2003, Bulger was summoned to a congressional hearing to testify about the case. But even though he was granted immunity from prosecution, when probed as to his connections with his brother, Billy gave evasive answers and demonstrated selective memory loss.

That such a morally compromised person could continue as the head of a state university system was considered nothing exceptional in the world of Irish Democratic politics in the Bay state. Billy could, after all, count on the support of Senator Edward Kennedy, Michael Dukakis and a host of other Massachusetts power brokers. But neither Billy nor his friends counted on the determination of Mitt Romney to make good on a campaign promise to oust the UMass president. Romney conducted a relentless campaign of pressure on Bulger to resign his office. He finally succeeded in August 2003 when Bulger quit.

Now that Whitey has finally been run to ground, it is appropriate for us to recall this odd chapter of political history and give Romney his due. Mitt Romney has been rightly accused of being a flip-flopper who will shift his views depending on the audience to which he is speaking or seeking votes. But whatever else you can say about him, he refused to play ball with the corrupt crowd running Massachusetts for decades. In bringing down Billy Bulger, he succeeded where other well-intentioned politicians and law enforcement officials failed. Though he hopes to achieve greater things in the future, the Bulger case may have been Romney’s finest hour to date.