On Thursday, Pence was subpoenaed by special counsel Jack Smith, who is investigating former President Donald Trump and his role in the January 6, 2021, insurrection.

The search comes after the FBI and the Justice Department’s National Security Division launched a review of the documents and how they ended up in Pence’s house. It is not yet clear what the documents are related to or their level of sensitivity or classification.

The Pence team, in talks with the Justice Department ahead of the search, expressed that they wanted to completely cooperate. The Pence team does not believe there are classified documents either at his home or at his office as they conducted what they considered an extensive search themselves, a source said.

Pence has previously acknowledged that “mistakes were made,” as he took responsibility for classified documents ending up in his home and pledged to would “fully cooperate” with any FBI investigation. He said that the found documents had been “immediately” secured and the National Archives was notified.

CNN first reported last month that Pence had discovered classified documents at his Carmel, Indiana, home after he instructed an attorney to search his records out of an “abundance of caution” following news of Biden’s classified documents. His attorney, Matt Morgan, found about a dozen documents marked as classified in four boxes that came from Pence’s vice presidential residence and his White House office.

Pence’s team notified the Archives of the discovery, and Archives officials notified the FBI. The FBI requested that Pence immediately turn over the classified documents and he agreed. The four boxes of unclassified material was driven to Washington so the Archives could review it for compliance with the Presidential Records Act, the law that requires all presidential documents are handed over to the Archives at the end of an administration.

The roughly 12 classified documents included materials described as background briefing memos that were prepared for Pence’s foreign trips, and sources described the classification markings as on the “lower level.” The boxes in question had not gone through the thorough procedures Pence’s office had in place for documents because they were packed at the last minute, sources said.

Biden’s team discovered classified documents at his Washington, DC, think tank office in November. Biden has said they immediately notified the National Archives, which then notified DOJ, but the discovery was not made public for weeks. Materials were also found at Biden’s Wilmington, Delaware, residence. On Wednesday, FBI agents also searched Biden’s home in Rehoboth Beach, Delaware, and did not discover any additional classified documents.

The FBI retrieved hundreds of documents from Trump’s Florida residence last August after he failed to comply with a subpoena to hand over classified material. Trump had more than 300 classified documents in his possession at Mar-a-Lago that were turned over to the Archives and retrieved by the FBI.

This story has been updated with additional details.