In a landmark case of brain drain, D.C. Mayor Muriel Bowser lost one of her most respected and capable hires last month when her ranking staff attorney quietly stepped down after three years of service.

The departure marks the latest in a series of Cabinet resignations during Bowser’s tenure. She is expected to win re-election to a second term with no viable opponents.

Mark Tuohey, a veteran Washington lawyer who in 2015 became the inaugural director of the Mayor’s Office of Legal Counsel (MOLC), left his post to accept an “of counsel” position at BakerHostetler, a Cleveland-based law firm with a D.C branch.

Tuohey enjoyed a reputation as the greatest legal mind on Bowser’s team and acted as a powerbroker in major disputes. He advised Bowser on a myriad of thorny issues, including the controversial merger of Pepco and Exelon, labor negotiations with firefighters, and, in recent weeks, whether she was to testify before the D.C. Council about the scandalous oustings of her public schools chancellor and deputy mayor for education.

Tuohey also provided guidance to the top lawyers at the District’s executive agencies. With his and other directors’ exits over the past three years, Bowser’s Cabinet looks significantly different than it did in 2015.

Tuohey’s departure has some Wilson Building wags wondering why he left the administration only a few months before the June 19 Democratic primary. But a District pol who knows him says Tuohey, who is in his early 70s, has wanted to move on “for quite some time.”

The D.C. government established MOLC after voters approved making the attorney general an elected position in 2010—a switch that took a few years to implement. In 2014, Tuohey ran for attorney general, but dropped out of the race within a month and said he would support Karl Racine. (Racine won.)

As MOLC director, he made $195,000 a year in salary as of December, public documents show. The office currently runs on a budget of more than $1.6 million and several full-time employees.

Now Tuohey will work on “white collar, investigation and securities enforcement and litigation” at BakerHostetler, the firm said in announcing his hire. A partner at the firm said Tuohey “is well known for his work as a top-notch litigator with deep connections in the District.”

Tuohey has been in the public eye for decades. The attorney served as head of the D.C. Bar; chair of the D.C. Sports and Entertainment Commission (which brought the Nationals to the District); defense counsel for former Police Chief Charles Ramsey in the Pershing Park mass arrests case; and defense counsel for Jeanne Clarke Harris, who pleaded guilty to federal charges in the protracted campaign-finance scandal that embroiled ex-Mayor Vince Gray. 

Tuohey also prosecuted those behind the 1977 Hanafi Siege of the then-District Building. Later, he assisted independent counsel Kenneth Starr in the Whitewater investigation into Bill and Hillary Clinton’s real estate investments.

Susana Castillo, a spokeswoman for Bowser, says the mayor’s office had anticipated Tuohey’s resignation. She adds that Ronald Ross, Tuohey’s deputy at MOLC, has been named director. Tuohey “worked tirelessly on behalf of all District residents for the past three years,” Castillo says in a statement. “We wish him well in his future endeavors.”

But he’s not completely separating himself from D.C. politics. In an interview, Tuohey says he will remain an informal adviser to Bowser “for as long as she’s mayor.” “I’m going to help her with any number of things down the road,” he says, praising Bowser’s leadership and character.

In March, Tuohey was in the news for meeting with At-Large Councilmember David Grosso, who chairs the Council’s education committee and had called for “an emergency hearing” about the resignation of former public schools Chancellor Antwan Wilson. After their meeting, Grosso reversed course and said he would wait for the results of independent investigations into the circumstances surrounding Wilson’s ousting instead of pursuing a hearing.

Tuohey says he spoke to the councilmember about the sensitivity of legislative investigations and the fact of a broad, ongoing review of schools by D.C. Inspector General Daniel Lucas. “It was obviously his decision to do what he was going to do,” Tuohey says of Grosso. “I think he made the right call.”

Both Castillo and Tuohey say the education issues had nothing to do with Tuohey’s departure. Tuohey explains that he’d been thinking about leaving the administration for roughly a year: He wanted to return to the private sector for his “swan song” and has dealt with multiple surgeries for arthritis. His wife also retired earlier this year.

“I decided it was time to slow down a little bit,” Tuohey says, denying any discontent with Bowser or the job. He says he told the mayor he was “prepared to stay on through the election in June,” but she was satisfied with the handling of legal issues. “The timing was not really an issue,” he adds.

Beyond his duties at BakerHostetler, Tuohey says he will teach a course at Fordham Law School, his alma mater, as an adjunct. And he plans to relax. “I can play a little more golf,” he says. “I feel very good about the work we’ve done and I look forward to the sort of last hurrah for the last few years.”

Tuohey isn’t the only prominent D.C. government attorney leaving. Ellen Efros, the Council’s general counsel, will soon step down for personal health reasons. The Council has posted a listing for the job, and Efros, who worked for the District government for about 15 years and has been with the Council for about three, says she’s helping with the search.

“I’m sad to leave,” she says. “I think it’s a great place to work with some strong legal talent.”