Robert S. Khuzami, the federal prosecutor in Manhattan who supervised the criminal case against President Trump’s former lawyer, is returning to the private sector as the top lawyer at Guggenheim Partners, the firm said on Tuesday.

Mr. Khuzami will be a managing partner at Guggenheim, which said in its announcement of his hiring that he would help steer the firm’s business operations in addition to running its legal and regulatory affairs.

Although Mr. Khuzami, 63, has previous Wall Street experience — he was general counsel for Deutsche Bank’s American arm in the 2000s — his job at Guggenheim will be his first senior role on the business side of a financial firm.

“His career in both private and public service makes him ideal for his new role at Guggenheim and we welcome him to our firm,” Mark Walter, Guggenheim’s chief executive, said in a statement.