WASHINGTON (AP) — Lawyers for former President Donald Trump have in recent months voluntarily turned over to federal investigators additional papers marked as classified, as well as a laptop belonging to a Trump aide, a person familiar with the situation said Friday night.

The legal team also provided an empty folder with classified markings, according to the person, who spoke on condition of anonymity to The Associated Press to discuss an ongoing investigation. It was not immediately clear what material was supposed to have been in the folder.

A Justice Department special counsel has been investigating the retention by Trump of hundreds of documents marked as classified at his Florida estate, Mar-a-Lago. FBI agents who served a search warrant at the property in August recovered roughly 100 classified documents, including records classified at the top-secret level.

A federal grand jury has been hearing evidence in the case for months. Prosecutors are investigating whether Trump willfully hoarded the material and whether he or anyone else sought to obstruct their probe, court filings show.

ABC News first reported the discovery of the additional documents.

The person familiar with the matter said a handful of pages with classified markings were found during a search weeks ago at the Mar-a-Lago complex that was supervised by the Trump legal team, and were promptly provided to the Justice Department. The documents were found in a box containing thousands of pages, the person said. The Trump legal team had enlisted investigators to search for any other classified documents that had not yet been recovered by the government.

Separately on Friday, the FBI searched the Indiana home of former Vice President Mike Pence and found an additional document with classified markings, following the discovery by his lawyers last month of sensitive documents. FBI officials have also searched the Delaware homes of President Joe Biden after his lawyers found documents with classified markings at his former office in Washington and at his Wilmington property.