In the most recent secret paper find, classified documents were discovered at the residence of former US Vice-President Mike Pence.
The materials, which were found by Mr. Pence’s attorney last week at his Indiana residence, have been given to the FBI.
Special investigators are already investigating how President Joe Biden and former President Donald Trump handled secret papers.
A criminal inquiry into Mr. Trump’s alleged file handling violations is ongoing.
Representatives for Mr. Pence informed the National Archives of the materials in a letter.
Lawyers said in a second letter that the FBI went to the former vice president’s house to acquire the documents, circumventing “normal protocols,” and asking for “direct custody” of them.
The Presidential Records Act mandates that after an administration is over, White House records be transferred to the National Archives. Such files must be securely stored in accordance with regulations.
At the conclusion of Donald Trump’s administration, a “limited number of documents with secret markings” were “inadvertently packaged and conveyed” to Mr. Pence’s residence, according to a letter from his attorney made public to US media.
After it became known that documents with classified markings were discovered in President Joe Biden’s Wilmington home, Mr. Pence requested counsel with experience handling sensitive information to review records at his home, the letter stated.
President doesn’t regret sharing confidential documents, according to the media
In the course of a 13-hour investigation of President Biden’s Delaware home on Friday, six additional top-secret documents were discovered.
According to a statement from Mr. Bauer on Saturday, the president provided access to his residence “to allow DoJ [the Department of Justice] to undertake a search of the full premises for potential vice-presidential records and potential classified information.”
The Penn Biden Centre, a Washington, DC-based think tank that the president created, was where a first batch of sensitive materials were discovered on November 2, according to Mr. Biden’s attorneys earlier this month.
His Wilmington home’s garage held a second set of documents that were discovered on December 20, and on January 12 a different document was discovered in a storage area, according to his attorneys.
The former president Donald Trump is also under investigation for his suspected handling of secret materials and his alleged refusal to comply with a subpoena at the same time as the finds at the houses of Mike Pence and Joe Biden.
At Mr. Trump’s Florida Mar-a-Lago residence, the FBI discovered hundreds of sensitive documents; Mr. Trump and his attorneys refused to turn over the data up until the Florida vacation home was searched by the FBI last August.
He asserted that President Biden was receiving preferential treatment from the FBI while denying any wrongdoing.