A Trump employee has told federal agents about moving boxes of documents at Mar-a-Lago at the specific direction of the former president, according to people familiar with the investigation, who say the witness account — combined with security-camera footage — offers key evidence of Donald Trump’s behavior as investigators sought the return of classified material.

The witness description and footage described to The Washington Post offer the most direct account to date of Trump’s actions and instructions leading up to the FBI’s Aug. 8 search of the Florida residence and private club, in which agents were looking for evidence of potential crimes including obstruction, destruction of government records or mishandling classified information.

The people familiar with the investigation said agents have gathered witness accounts indicating that, after Trump advisers received a subpoena in May for any classified documents that remained at Mar-a-Lago, Trump told people to move boxes to his residence at the property. That description of events was corroborated by the security-camera footage, which showed people moving the boxes, said the people, who spoke on the condition of anonymity to discuss an ongoing investigation.

Spokespeople for the Justice Department and FBI declined to comment.

Trump spokesman Taylor Budowich declined to answer detailed questions for this article. “The Biden administration has weaponized law enforcement and fabricated a Document Hoax in a desperate attempt to retain political power,” Budowich said in a statement. “Every other President has been given time and deference regarding the administration of documents, as the President has the ultimate authority to categorize records, and what materials should be classified.”

Budowich accused the Justice Department of a “continued effort to leak misleading and false information to partisan allies in the Fake News,” and said that to do so “is nothing more than dangerous political interference and unequal justice. Simply put, it’s un-American.”

The employee who was working at Mar-a-Lago is cooperating with the Justice Department and has been interviewed multiple times by federal agents, according to the people familiar with the situation, who declined to identify the worker.

In the first interview, these people said, the witness denied handling sensitive documents or the boxes that might contain such documents. As they gathered evidence, agents decided to re-interview the witness, and the witness’s story changed dramatically, these people said. In the second interview, the witness described moving boxes at Trump’s request.

The witness is now considered a key part of the Mar-a-Lago investigation, these people said, offering details about the former president’s alleged actions and instructions to subordinates that could have been an attempt to thwart federal officials’ demands for the return of classified and government documents.

Multiple witnesses have told the FBI they tried to talk Trump into cooperating with the National Archives and Records Administration and the Justice Department as those agencies for months sought the return of sensitive or historical government records, people familiar with the situation said.

But entreaties from advisers and lawyers who pushed for Trump to hand the documents back fell on deaf ears with Trump, these people said, speaking on the condition of anonymity to discuss private conversations. Trump grew angry this spring after a House Oversight Committee investigation was launched, telling aides they’d “screwed up” the situation, according to people who heard his comments. “They’re my documents,” Trump said, according to an aide who spoke to him.

The details shared with The Post reveal two key parts of the criminal probe that until now had been shrouded in secrecy: an account from a witness who worked for and took directions from Trump, and the way that security footage from Mar-a-Lago has played an important role in buttressing witness accounts.

Together, those pieces of evidence helped convince the FBI and Justice Department to seek the court-authorized search of Trump’s residence, office and a storage room at Mar-a-Lago, which resulted in the seizure of 103 documents that were marked classified and had not been turned over to the government in response to the May subpoena. Some of the documents detail top-secret U.S. operations so closely guarded that many senior national security officials are kept in the dark about them. The Aug. 8 search also yielded about 11,000 documents not marked classified.

The failure or possible refusal to return the classified documents in response to the subpoena is at the heart of the Justice Department’s Mar-a-Lago investigation, which is one of several high-profile, ongoing probes involving Trump. The former president remains the most influential figure in the Republican Party and talks openly about running for the White House again in 2024.

Within Trump’s orbit, there have been months of dueling accusations and theories about who may be cooperating with the federal government. Some of the former president’s closest aides have continued to work with Trump even as they have seen FBI agents show up at their houses to question them and serve subpoenas.

Within the Justice Department and FBI, the witness’s account has been a closely held secret as agents continue to gather evidence in the high-stakes investigation. In addition to wanting to keep the information they have gathered so far under wraps, people familiar with the situation said, authorities are also concerned that if or when the witness’s identity eventually becomes public, that person could face harassment or threats from Trump supporters.

In a filing to the Supreme Court on Tuesday, Justice Department lawyers appeared to allude to witness accounts and the video footage when they wrote: “The FBI uncovered evidence that the response to the grand jury subpoena was incomplete, that additional classified documents likely remained at Mar-a-Lago, and that efforts had likely been taken to obstruct the investigation.”

Since the Aug. 8 search, Trump has offered a number of public defenses of why documents with classified markings remained at Mar-a-Lago — saying he declassified the secret documents, suggesting that the FBI planted evidence during the search, and suggesting that as a former president he may have had a right to keep classified documents. National security law experts have overwhelmingly dismissed such claims, saying they range from far-fetched to nonsensical.

Officials at the National Archives began seeking the return of documents last year, after they came to believe that some presidential records from the Trump administration — such as letters from North Korean leader Kim Jong Un — were unaccounted for, and perhaps in Trump’s possession.

After months of back-and-forth, Trump agreed in January to turn over 15 boxes of material. When archivists examined the material, they found 184 documents marked classified, including 25 marked top secret, which were scattered throughout the boxes in no particular order, according to court filings.

That discovery suggested to authorities that Trump had not turned over all the classified documents in his possession. In May, a grand jury subpoena demanded the return of classified documents with a wide variety of markings, including a category used for secrets about nuclear weapons.

In response to that subpoena, Trump’s advisers met with government agents and prosecutors at Mar-a-Lago in early June, handing over a sealed envelope containing another 38 classified documents, including 17 marked top secret, according to court papers. According to government filings, Trump’s representatives claimed at the meeting that a diligent search had been conducted for all classified documents at the club.

That meeting, which included a visit to the storage room where Trump’s advisers said the relevant boxes of documents were kept, did not satisfy investigators, who were not allowed to inspect the boxes they saw in the storage room, according to government court filings.

Five days later, senior Justice Department official Jay Bratt wrote to Trump’s lawyers to remind them that Mar-a-Lago “does not include a secure location authorized for the storage of classified information.” Bratt wrote that it appears classified documents “have not been handled in an appropriate manner or stored in an appropriate location.”

“Accordingly, we ask that the room at Mar-a-Lago where the documents had been stored be secured and that all of the boxes that were moved from the White House to Mar-a-Lago (along with any other items in that room) be preserved in that room in their current condition until further notice.”

Agents continued to gather evidence that Trump was apparently not complying with either government requests or subpoena demands. After significant deliberation, aware that it would be highly unusual for federal agents to search a former president’s home, they decided to seek a judge’s approval to do so.

That Aug. 8 search turned up, in a matter of hours, 103 documents marked classified, including 18 marked top secret, according to court papers. The stash included at least one document that described a foreign country’s military defenses, including its nuclear capabilities.