Khuzami was born in Brooklyn (you can’t understand the Trump presidency without understanding the resentments and cultural geography of the New York boroughs) and raised in Rochester. According to a 2013 Times DealBook story, he was born into a bohemian family, with ballroom-dancer parents, a muralist sister and a drummer brother. They joke that Robert is the “white sheep” in the family.

He began college at the State University of New York at Geneseo before transferring to the University of Rochester. He supported himself as a dishwasher, bartender and overnight dockworker. He went to Boston University law school and his career took off.

Khuzami has served through three separate intense investigations. In the 1990s he was part of the team that prosecuted Omar Abdel Rahman, the “Blind Sheikh,” who led a foiled plot to blow up the United Nations and other landmarks. In 2009, in the wake of the financial crash, he was named head of enforcement at the Securities and Exchange Commission, revitalizing a demoralized unit. And now he is part of a team taking on the president of the United States.

In between his government service, he’s taken lucrative private sector jobs, as general counsel for Deutsche Bank and as a partner at Kirkland & Ellis.

Andy McCarthy was one of Khuzami’s fellow prosecutors in the Blind Sheikh case. In his book “Willful Blindness,” McCarthy describes Khuzami as fearless, dogged and willing to contend with the thorniest knots of evidence. In an email to me, McCarthy wrote that Khuzami “is as terrific as you may suspect he is.”

Over the years, Khuzami’s employees have generally described him as intimidating but likable. He was intimidating after the financial crisis. In the 2011 fiscal year, for example, the S.E.C. brought a record 735 enforcement actions. In the same year, his division collected $2.8 billion in penalties and disgorgement.

His critics have often come from the left. Khuzami spoke at the 2004 Republican National Convention, in defense of the Patriot Act. Some argue, plausibly, that as general counsel to Deutsche Bank from 2004 to 2009, he should have been aware of the financial shenanigans of that era. Others argue that since he’s been through the revolving door between the elite firms and big government, he’s actually been soft on Wall Street bigs, charging them penalties but not actually holding them responsible.