The letter was short, sharply worded and stamped “CONFIDENTIAL.” It stayed that way for less than a day.

The June 2012 missive to top city officials — detailing concerns about the District’s chief administrative law judge and signed by 15 subordinate judges — laid bare one of the city government’s most contentious workplaces.

It also heightened a confrontation that has since led to several investigations, the hiring of big-name law firms, a union organizing drive, the mass resignation of a blue-ribbon oversight commission and, now, high-profile ethics charges.

“It’s a mess,” said D.C. Council Chairman Phil Mendelson (D), who has monitored the conflict and intervened at several junctures. “We have an agency in turmoil.”

At the center of the tumult is Mary Oates Walker, a Howard University-trained former corporate lawyer who has served as chief of the D.C. Office of Administrative Hearings since 2009. She oversees more than two dozen administrative judges who resolve disputes over such matters as welfare eligibility and licensing applications.

Mary Oates Walker, left, and Stacie Turner of "DC Housewife" fame are seen at the Washington Ballet's annual "Nutcracker" Tea Party held at the Willard Intercontinental Hotel in Washington. (Rebecca D'Angelo/For The Washington Post)

According to Walker and her allies, she has been a diligent reformer, bringing standards and accountability to underperforming judges who had amassed a backlog of undecided cases.

But some of those judges say she has been a tyrannical manager, hiring and rewarding close allies while treating others in ways that the letter described as “unprofessional, erratic, and at times demeaning.”

“When you have such a bad relationship with more than half of your employees . . . you don’t have an employee problem, you’ve got a management problem,” said Paul Shearon, a top official with the union that has attempted to organize the junior judges. (Several judges involved in the dispute declined to comment because of the litigation and referred requests for comment to Shearon.)

Walker is now in a high-stakes fight for her job, her reputation and, perhaps, even her law license after the District’s ethics board charged her this month with 19 counts of wrongdoing. The allegations, which could result in significant fines and potential bar sanctions, are rooted in business dealings with a friend and deputy, as well as alleged attempts to mislead investigators and retaliate against the judges who signed the 2012 letter.

The Board of Ethics and Government Accountability is scheduled to hear charges next month involving Walker and the deputy, Kiyo Oden Tyson, the agency’s general counsel, who faces 10 counts. But Walker and Tyson are seeking to have the charges invalidated in court, and they portray themselves as victims of disgruntled bureaucrats and the political machinations of Mayor Vincent C. Gray (D).

“She came in to hold them accountable, and this is the backlash that she faces,” said James F. Hibey, an attorney for Walker. Any competent successor, he added, would face the same problems.

The ethics charges against Walker and Tyson came about a year and a half after a WJLA (Channel 7) report examined how a $43,000 moving contract came to be awarded to a company owned by the man who is now Tyson’s husband. The judges’ letter, which questioned the contract and overall management of the office, was sent and publicized days later.

A D.C. law firm, Leftwich & Ludaway, independently investigated the judges’ allegations. Its report has not been publicly released, but references in public documents indicate that the inquiry found little support for many of the judges’ allegations. What it did find was the appearance of a conflict of interest because Walker and Tyson had once owned a real estate business together.

The District’s inspector general, meanwhile, had looked into the contracting matter and found no evidence that Walker or Tyson had acted improperly.

The law firm’s report was forwarded to the Commission on the Selection and Tenure of Administrative Law Judges, as well as to the ethics board. In August, the commission moved to investigate the 15 judges, following the law firm’s determination that many of the allegations in their initial letter were unfounded.

Gray and Mendelson intervened, urging the body’s three voting members in an Oct. 23 letter to “terminate this investigation promptly” because it would have a “chilling effect” on whistleblowers and prolong internal turmoil.

The commission members — a D.C. Superior Court judge, a former chief lawyer to the D.C. Council and a respected former administrative law judge — resigned two days later, saying the political intervention had “tied our hands” and kept them from fulfilling their legal responsibilities. The commission has been dormant since.

Ethics board investigators pressed ahead, finding evidence that Walker steered the contract to the firm owned by Tyson’s now-husband and that she used her public office for private gain by hiring Tyson and putting her in a position to support their outside business interests. They also found evidence that Walker retaliated against the 15 judges who signed the 2012 letter by helping to instigate the commission’s abortive investigation. (Walker sits on the commission as an ex officio member.)

On Feb. 7, a day after the ethics board delivered its initial charges, Gray moved to fire Walker. “Each of these charges, whether proven or not, has created such a cloud on your ability to serve as the head of a neutral, quasi-judicial body as to warrant dismissal for cause,” he wrote.

Walker is now on leave, and her interim replacement — Judge Wanda R. Tucker, one of the signers of the 2012 letter — has moved to fire Tyson and cut ties with the outside law firm that Walker hired to fight the unionizing effort.

Shearon, secretary-treasurer of the International Federation of Professional and Technical Engineers, said the ethics charges have vindicated the judges’ concerns. Walker’s response, he said, has been to “try to create a diversion and point to everybody else, including the people who blew the whistle on her.”

Walker and her attorneys accused the ethics investigators of ignoring key information, including evidence that Walker’s supposedly misleading comments were inadvertent. They also obtained statements from the three commission members who resigned that Walker had no role in the decision to investigate the judges who signed the initial letter.

“Any suggestion that Chief Judge Walker, or anyone else, improperly influenced us to initiate an investigation that was clearly legally and factually warranted is specious and insulting,” Superior Court Judge Gregory E. Jackson said in his statement.

Hibey also suggested that political considerations might have influenced the Gray administration’s move to fire Walker. Walker, a former in-house counsel for the Hershey Corp., was appointed to her six-year term by then-Mayor Adrian M. Fenty (D), whom Gray ousted. Hibey also noted that the judges’ organizing campaign has been strongly backed by labor groups that support Gray.

Pedro Ribeiro, a spokesman for Gray, declined to address the particulars of Walker’s assertions, but he rejected the idea that the move to fire her was motivated by animus toward Fenty. He noted that Police Chief Cathy L. Lanier and Schools Chancellor Kaya Henderson, among others, served under Fenty and remain in their posts.