Rod J. Rosenstein, the former No. 2 Justice Department official whose tumultuous two-year tenure was defined by the special counsel investigation he initiated, is joining the King & Spalding law firm’s special government investigations team, the firm announced Wednesday.

A longtime U.S. attorney tapped by President Trump to be the deputy attorney general, Rosenstein dealt with high-profile controversy within weeks of assuming his post, continuing almost to the moment when he left government in May.

Before he was in the job a month, Rosenstein, at Trump’s request, wrote a memo to support the firing of FBI Director James B. Comey — a move that plunged the bureau and the Justice Department into chaos, as many feared the president was trying to thwart an investigation into possible coordination between his 2016 campaign and Russia.

Rosenstein then appointed Robert S. Mueller III as special counsel to lead that investigation and restore public faith in the process. But in doing so, he drew the ire of the commander in chief, who toyed intermittently with firing Rosenstein along with Attorney General Jeff Sessions, whose recusal from the Russia case left Rosenstein to supervise the matter.

In an interview, Rosenstein declined to address most of the politically thorny moments during his tenure as deputy attorney general — including his reported assurances to Trump about the Mueller investigation, the allegation that he suggested wearing a wire to surreptitiously record the president and his reaction to the inspector general’s review of the Russia case.

He conceded that, “certainly in retrospect there are things that I might do differently,” but also asserted, “I think we got all the big issues right.”

Rosenstein notably stood by giving Trump a memo used to fire Comey.

“No,” Rosenstein said, when asked if he regretted the move. “I would have written that memo if any president asked me about my opinion about Jim Comey, and as you know, my view was 100 percent vindicated by the lengthy and detailed inspector general investigation. And my dispute with Mr. Comey was not personal. He violated some very important principles, and that’s consistent with what the inspector general found.”

The inspector general rebuked Comey for his handling of the Hillary Clinton email investigation; in supporting Comey’s firing, Rosenstein expressed similar concerns.

Lawyers for Comey did not immediately return messages seeking comment.

Rosenstein said that while his handling of the Russia case might have attracted media attention, “when I look back at my tenure at the department, it was mostly not about Russia.” He said he considered among his most significant accomplishments the rewriting of the Justice Department policy manual, the development of a new corporate fraud enforcement policy and the efforts the department made to curb opioid overdose deaths and violent crime.

He said he maintained a good relationship with officials in the Trump administration, and while he conceded his relationship with the president had “ups and downs,” he asserted, “I think I left on relatively good terms.”

Rosenstein said he chose King & Spalding because of the firm’s international profile and “collegial culture.” He said he had been impressed with lawyers from the firm with whom he worked over the years.

King & Spalding has added several former high-profile officials in recent months and years, including former deputy attorney general Sally Yates, former director of national intelligence Daniel Coats, former U.S. attorneys Zachary Fardon and John Horn, and former FBI chief of staff Zack Harmon.

Wick Sollers, chair of the firm’s special matters and government investigations practice, said: “Rod deserves his well-earned reputation for being decisive and unflappable in extraordinary professional situations. His experiences conducting and supervising large criminal and civil litigation uniquely qualify him to counsel and defend clients facing complex investigations, lawsuits and enforcement matters.”

Rosenstein had served in the Justice Department in both Democratic and Republican administrations before being nominated as deputy attorney general by Trump, and he generally enjoyed a reputation as a nonpartisan prosecutor. He served as the U.S. attorney in Maryland from 2005 to 2017, during the administrations of President George W. Bush and President Barack Obama.

Had he not been selected by Trump for the Justice Department leadership post, Rosenstein might have been little known outside of the Maryland and D.C. legal communities. But his role in the firing of Comey and his appointment and supervision of Mueller soon made him a household name — and presented him with unprecedented challenges.

Rosenstein was particularly on edge during the time when Comey was fired, people familiar with the events of that time say. Though Rosenstein wanted Comey gone over concerns about his handling of the Clinton email case, the president had other reasons — including that Comey would not say publicly the president wasn’t personally being investigated in the Russia case.

When Mueller’s team questioned the deputy attorney general about that time period, he had to pause, “appearing to have been overcome by emotion,” according to a government account of the interview.

Rosenstein was particularly upset with how the firing was initially blamed largely on him. Trump, though, ultimately conceded in a televised interview he had resolved to remove his FBI director no matter what other officials recommended, and was thinking about the Russia case when he did so.

Former acting FBI director Andrew McCabe alleged that Rosenstein at one point after Comey was fired suggested he could wear a wire to surreptitiously monitor the president — a dramatic move that was never executed. Rosenstein’s defenders have said the suggestion was not considered seriously.

When discussions about the matter were reported in the fall of 2018 by the New York Times — and Rosenstein’s job again seemed in jeopardy — Rosenstein sought to defuse the volatile situation and assure Trump that he would be treated fairly in the investigation, according to people familiar with matter.

“I give the investigation credibility,” Rosenstein said, according to an administration official with knowledge of what was said during the call. “I can land the plane.”