Several top prosecutors in the U.S. attorney’s office in Washington, D.C., were demoted on Friday to low-level positions handling minor crimes, another step in a campaign of retribution against Justice Department officials perceived as enemies by the Trump administration.

Those demoted include one prosecutor who had overseen all cases arising from the events of Jan. 6, 2021, and at least two who had worked on the trials of members of the Proud Boys and Oath Keepers militia, according to people with knowledge of the moves, who spoke on condition of anonymity because they were not authorized to speak publicly.

The abrupt personnel changes, announced in a series of emails sent by Ed Martin, the interim U.S. attorney in Washington, were the latest upheavals in one of the country’s most important federal prosecutors’ offices.

Mr. Martin’s internal onslaught has been seen by prosecutors in the office as a brazen effort to punish, humble and harness its employees at the behest of the White House. Demeaning demotions have been a favored tactic employed by President Trump’s political appointees to force career prosecutors to quit.

Among those being reassigned was John Crabb Jr., a supervisor whose experience in the office had earned him some of the toughest assignments in recent years, the people familiar with the moves said.

Those included the criminal trial of Roger J. Stone Jr., one of Mr. Trump’s advisers; the prosecution of Michael T. Flynn, a former national security adviser; and all conspiracy cases arising from the Capitol attack on Jan. 6, including those that involved the Proud Boys and Oath Keepers.

Mr. Crabb also worked as the lead prosecutor in the case of a Libyan man convicted of terrorism charges stemming from the attack on the U.S. mission in Benghazi in 2012.

Another prosecutor who was reassigned, the people said, was Greg Rosen, who had overseen all Jan. 6-related cases as the chief of what was known as the Capitol Siege section.

The steps taken to give Mr. Crabb and Mr. Rosen new jobs well below their former ranks came less than a month after Mr. Martin oversaw the dismissal of more than a dozen newly hired prosecutors who worked on Jan. 6 cases. Mr. Martin has also threatened Democratic politicians with investigations related to their public statements about his political allies, including Elon Musk.

Last week, the highly regarded head of the office’s criminal division, Denise Cheung, resigned after she declined a request from Mr. Martin and other Justice Department officials to freeze the assets of a government contractor, saying she had insufficient evidence to do so.

Her position — a vital slot responsible for addressing crime in the nation’s capital — has remained unfilled, leaving prosecutors in the already demoralized office without clear leadership, according to a person with knowledge of the situation.

Mr. Trump has nominated Mr. Martin, who had no previous prosecutorial experience — and little interaction with the nonpartisan career prosecutors who work for him — as the permanent U.S. attorney in Washington. His confirmation hearing has yet to be scheduled.

The gutting of much of his top staff is one of the most significant moves made so far by Mr. Martin, who himself was outside the Capitol on Jan. 6, served on the board of an organization that raised legal fees for the rioters and worked as a defense lawyer for some of them.

Mr. Martin’s office is also defending the Trump administration against a First Amendment lawsuit brought by The Associated Press, whose reporters have been barred from covering some presidential events. Before a recent hearing, he posted a message on social media describing himself and members of his staff as “President Trump’s lawyers.”

One of the prosecutors reassigned on Friday from a supervisory position to working on small-time misdemeanor cases was Jason McCullough, the people familiar with the matter said. Mr. McCullough played a central role in investigating and prosecuting several Proud Boys, including five members of the far-right group who stood trial on charges of seditious conspiracy stemming from the Capitol attack and were sentenced to significant prison terms.

Another senior prosecutor, Kathryn Rakoczy, was demoted from working on federal cases to local cases in Superior Court. Ms. Rakoczy was part of a team that secured sedition convictions arising from Jan. 6 against Stewart Rhodes, the leader of the Oath Keepers, and one of his lieutenants.

A spokesman for Mr. Martin did not immediately return a request for comment.

Mr. Martin did not call the prosecutors about their reassignments or inform them in person about the changes. Instead, he sent the prosecutors — some of the most experienced in his office — a terse email from his phone informing them that they would “immediately” be assigned to new divisions many rungs below them on the career ladder, according to a screenshot provided to The New York Times.

He told one veteran official, who was being moved to the misdemeanors division — which brings cases against people accused of offenses like public drunkenness and shoplifting — to transfer his current cases to members of his unit.

“Let me clear: this change is not temporary,” Mr. Martin wrote.