Longtime deputy solicitor general Michael Dreeben, who has argued 105 cases before the Supreme Court and left the Justice Department after serving as part of special counsel Robert S. Mueller III’s investigation team, is joining the Washington office of O’Melveny & Myers, the law firm announced Tuesday.

Dreeben, who served in the solicitor general’s office since 1988, will become a partner in the appellate and white-collar practice. A news release announcing his hiring said he would also provide “crisis management counsel to boardroom clients, especially those facing government investigations and complex issues of first impression.”

Dreeben, 65, was responsible for the criminal docket in the solicitor general’s office, which represents the government in the courts of appeals and the Supreme Court. He is widely respected for his expertise in the field and trusted by Supreme Court justices, whom he has worked with in the solicitor general’s office and opposed in court when they were in private practice.

His departure from the Justice Department earlier this year was enough of an event that Scotusblog.com, the private website devoted to coverage and discussion of the Supreme Court, invited tributes to Dreeben.

Solicitor General Noel Francisco, President Trump’s choice for the job, wrote that “Michael Dreeben knows more about criminal law than anyone else on Earth.”

Francisco said he has also faced off against Dreeben at the Supreme Court, and he praised him as an advocate. “Even as he’s winning with his arguments, you can’t help feeling that he could win with your arguments, too,” Francisco wrote.

Working for Mueller, Dreeben’s role included fending off challenges to the special counsel’s authority. When former Trump campaign chairman Paul Manafort challenged Mueller’s investigation into his business dealings in Ukraine, Dreeben was the lawyer who argued in court that the special counsel was operating within his scope.

Dreeben similarly argued against a challenge from Andrew Miller, an associate of Trump’s longtime friend Roger Stone who said that Mueller’s appointment was unconstitutional because of the manner in which he was named to his post.

In an interview, Dreeben said the Mueller experience “awakened” in him the desire to expand his practice beyond arguments at the Supreme Court. “I felt it was time to try something new,” he said. “What I’ve landed on seems like a great combination.”

Trump has been sharply critical of Mueller and his investigation. But Dreeben denied it would have been uncomfortable for him to return to the solicitor general’s office and the Justice Department, or that he would have been unwelcome there.

“No, no, it was 100 percent my decision,” Dreeben said.

One of the draws at O’Melveny, Dreeben said, was the chance to be reunited with Walter Dellinger, a former acting solicitor general and one of Dreeben’s law professors at Duke.