The New York Times reported that sensitive White House records were found in Donald Trump's office and in the basement of Mar-a-Lago.
The publication reported on Monday that Trump and his aides returned about 150 classified documents to the National Archives and Records Administration before the FBI raided the former president's home.
According to The Times, one set of documents had top secret information.
It's not known how these documents are traditionally stored in the White House or how they would be stored in the National Archives, but several people familiar with the investigation told The Times that the FBI found documents in a container that was in a closet in Trump's office.
There was a set of documents in the basement.
Two former White House officials who were tasked with representing the former president to the National Archives were contacted by the agency and tried to get the documents back, but they were turned down by Trump.
All official material must be handed over to the National Archives when a president leaves office.
A representative for Trump did not respond to the request for comment.