The day before a key meeting last year between a lawyer for former President Donald J. Trump and officials seeking the return of classified documents in Mr. Trump’s possession, a maintenance worker at the former president’s private club saw an aide moving boxes into a storage room, according to a person familiar with the matter.
The maintenance worker offered to help the aide — Walt Nauta, who was Mr. Trump’s valet in the White House — move the boxes and ended up lending him a hand. But the worker had no idea what was inside the boxes, the person familiar with the matter said. The maintenance worker has shared that account with federal prosecutors, the person said.
The worker’s account is potentially significant to prosecutors as they piece together details of how Mr. Trump handled sensitive documents he took with him from the White House upon leaving office and whether he obstructed efforts by the Justice Department and the National Archives to retrieve them.
Mr. Trump was found to have been keeping some of the documents in the storage room where Mr. Nauta and the maintenance worker were moving boxes on the day before the Justice Department’s top counterintelligence official, Jay Bratt, traveled to Mar-a-Lago last June to seek the return of any government materials being held by the former president.
Mr. Nauta and the worker moved the boxes into the room before a search of the storage room that same day by M. Evan Corcoran, a lawyer for Mr. Trump who was in discussions with Mr. Bratt. Mr. Corcoran called Justice Department officials that night to set up a meeting for the next day. He believed that he did not have a security clearance to transport documents with classified markings, a person briefed on his decision said.
Weeks earlier, the Justice Department had issued a subpoena demanding the return of the documents. Prosecutors have been trying to determine whether Mr. Trump had documents moved around Mar-a-Lago or sought to conceal some of them after the subpoena.
Part of their interest is in trying to determine whether documents were moved before Mr. Corcoran went through the boxes himself ahead of a meeting with Justice Department officials looking to retrieve them. Prosecutors have been asking witnesses about the roles of Mr. Nauta and the maintenance worker, whose name has not been publicly disclosed, in moving documents around that time.
During his trip to Mar-a-Lago on June 3, Mr. Bratt was given a packet of roughly three dozen documents with classified markings by a lawyer for Mr. Trump. Mr. Bratt was also given a letter, drafted by Mr. Corcoran but signed by another lawyer for the former president, attesting that a diligent search had been carried out for any additional material in response to the subpoena and that none had been found. Mr. Bratt was not given access to search the storage room at that point.
The detail about the timing of Mr. Nauta’s interaction with the maintenance worker was reported earlier by The Washington Post. A lawyer for Mr. Nauta declined to comment. A lawyer for the maintenance worker would not publicly discuss the matter.
The New York Times reported this month that prosecutors had obtained cooperation from a witness who worked at Mar-a-Lago. Among other things, the witness provided investigators with a picture of the storage room.
The investigation, overseen by the special counsel, Jack Smith, has shown signs of entering its final phases, and this week lawyers for Mr. Trump — who is the current front-runner for the 2024 Republican presidential nomination — asked for a meeting to discuss the case with Attorney General Merrick B. Garland.
Steven Cheung, a spokesman for Mr. Trump, called the investigation a “targeted, politically motivated witch hunt against President Trump that is concocted to meddle in an election and prevent the American people from returning him to the White House.”
He added that prosecutors have “harassed anyone and everyone who works, has worked or supports President Trump” and maintained that Mr. Trump had tried to cooperate with the Justice Department.
Prosecutors have been questioning witnesses about Mr. Trump’s possible motive for having the documents.
They have subpoenaed information about Mr. Trump’s business deals with foreign countries since he became president. And they have been told by witnesses that some aides may have known Mr. Trump still had documents in his possession after an initial 15 boxes of government material — found to contain classified documents — were turned over to the National Archives in January 2022 after persistent efforts by the archives to retrieve the material, according to people briefed on the matter.
Among the most prominent witness in recent months has been Mr. Corcoran, who met with Mr. Bratt of the Justice Department last June and drafted the letter stating that a diligent search had turned up no further documents.
In March, prosecutors successfully pierced Mr. Corcoran’s attorney-client privilege with Mr. Trump under the crime-fraud exception, a provision of the law that can be used when investigators have evidence that a lawyer’s services may have been used in the commission of a crime.
Judge Beryl A. Howell, then the chief judge presiding over grand jury matters in Federal District Court in Washington, found that prosecutors had sufficiently demonstrated evidence that Mr. Trump knowingly misled Mr. Corcoran about what documents he still possessed.
The Times previously reported that Judge Howell, writing in a sealed memorandum, described what she called Mr. Trump’s “misdirection” in dealing with the National Archives in 2021 and early last year, saying it was “apparently a dress rehearsal” for how he handled the grand jury subpoena last May, according to a person briefed on the memo’s contents.
In the sealed memo laying out her reasoning for ruling that Mr. Corcoran should not be protected by attorney-client privilege, Judge Howell touched on numerous instances of what prosecutors considered to be evidence of possible obstruction and wrongful possession of government material on Mr. Trump’s part, the person briefed on its contents said.
“Other evidence demonstrates that the former president willfully sought to retain classified documents when he was not authorized to do so, and knew it,” Ms. Howell wrote, the person said.
Judge Howell acknowledged that the standard for meeting the crime-fraud exception is lower than what would be required to bring charges or win a jury verdict, according to the person familiar with what she wrote. Still, the judge made clear she believed the government had met the threshold, for both obstructing the grand jury proceeding and “unauthorized retention of national defense information,” the person said.
“The government has proffered sufficient evidence that the former president possessed tangible documents containing national defense information,” she wrote, adding that they showed he “failed to deliver those documents to an officer entitled to receive them.”
At another point, Judge Howell addressed Mr. Trump’s intent and state of mind, saying that the government had also provided sufficient evidence to meet its burden of showing that the former president had retained the classified documents willfully, the person said.
She also noted that a further search of Trump properties late last year, conducted by experts on Mr. Trump’s behalf after pressure from prosecutors, turned up additional documents with classified markings in his bedroom at Mar-a-Lago, the person briefed on the document said.
“Notably, no excuse is provided as to how the former president could miss the classified-marked documents found in his own bedroom at Mar-a-Lago,” Judge Howell wrote, according to the person briefed on the contents of her memo.