The Justice Department has moved on two fronts to chip away at some of the last traces of its vast investigation into the attack on the Capitol on Jan. 6, 2021, aligning itself ever more closely with President Trump’s own efforts to whitewash the events of that day.

On Friday evening, just as the holiday weekend was beginning, federal prosecutors in Washington filed motions to formally dismiss the most serious criminal cases stemming from Jan. 6 — those that involved leaders and members of far-right groups who were tried and convicted on charges of seditious conspiracy.

Hours later, one of the Justice Department’s official social media accounts confirmed that the department was scrubbing its online archives of news releases used to publicize the cases filed against Jan. 6 rioters.

The investigation of the riot at the Capitol, which stretched from 2021 to 2025, was the single largest criminal inquiry in the Justice Department’s history, resulting in charges being filed against nearly 1,600 defendants. But ever since Mr. Trump began his second term by granting clemency to all of the defendants, the department has taken steps to unwind almost every aspect of its enormous effort to hold the rioters accountable for disrupting the peaceful transfer of presidential power after the 2020 election.

Senior department officials, including Todd Blanche, the acting attorney general, were, for instance, deeply involved in setting up a $1.8 billion fund this week intended to compensate allies of Mr. Trump who believe they were wronged in the courts by previous Democratic administrations. Many Jan. 6 rioters were elated by the creation of the fund, and have already vowed to file claims seeking payouts.

The motions to dismiss the sedition cases against a dozen members of the far-right groups the Proud Boys and the Oath Keepers was another step toward wiping away the vestiges of what had been the most significant criminal proceedings arising from the Capitol attack. While all of the men were pardoned or had their sentences commuted by Mr. Trump, the full dismissal of their charges would represent a further symbolic victory, and would allow the veterans among them to reclaim military benefits that were terminated after their convictions.

The two federal judges who oversaw the trials — Timothy J. Kelly and Amit P. Mehta — will still have to sign off on the department’s request to dismiss the cases outright. In their motions filed in Federal District Court in Washington on Friday, prosecutors said the government had determined that dismissal was in the “interests of justice.” But the judges could push back and ask how justice would actually be served by throwing out the cases.

When Mr. Trump returned to the White House, officials quickly shut down a page on the Justice Department’s website housing a database of all of the Jan. 6 defendants with details about the charges they faced. But news releases sent out informing the public about updates in the cases had lingered on the site — at least until recently.

On Friday afternoon, a reporter for The Washington Post posted a message on social media taking note of the fact that some of the news releases were being quietly removed from the department’s archives — among them, one describing the 74-month prison sentence received by Andrew Taake, who pleaded guilty to attacking the police with bear spray and a metal whip.

A Justice Department social media account quickly posted its own message responding to the reporter and declaring that there was nothing quiet about what the department was doing.

“We are proud to reverse the DOJ’s weaponization under the Biden administration,” the message read. “We will do everything in our power to make whole those who were persecuted for political purposes. This includes stripping DOJ’s website of partisan propaganda.”