Federal prosecutors in the United States have opened a grand jury investigation into whether former President Donald Trump mismanaged records that ended up at his Florida residence after his departure from the White House, according to a New York Times report released Thursday, citing two people briefed on the issue.

Prosecutors have issued a subpoena to the National Archives and Records Administration (NARA) to obtain the documents, the report said. Authorities have also made interview requests to people who worked in the White House in Trump's final days in office, it said.

A grand jury probe suggests the Justice Department has advanced in its inquiry, which began after NARA said it had recovered 15 boxes of documents, including classified records, that Trump took to his Mar-a-Lago estate when he left the White House in January 2021.

The Justice Department did not immediately respond to a request for comment.

Trump representatives did not immediately respond to a request for comment. Trump has previously confirmed that he agreed to return certain records to the National Archives, calling it "an ordinary and routine process."

A federal law called the U.S. Presidential Records Act requires the preservation of memos, letters, notes, emails, faxes and other written communications related to a president's official duties.

Last month, Trump was found in contempt of court by a New York judge for failing to produce documents subpoenaed in the state attorney general's civil probe of his business practices. The judge ruled Trump was to pay $10,000 a day until he complies and should he fail to pay, he would be jailed.