Joe Biden’s White House physician on Wednesday declined to answer questions during a closed-door deposition with the House Oversight Committee, invoking his Fifth Amendment right as the Republican-led panel pushes forward in its probe of the former president’s mental fitness and decline.

Biden has strongly denied that he was not in a right state of mind at any point while in office, calling the claims “ridiculous and false.”

The committee is investigating Biden's decline while in office, and O'Connor had regular access to Biden during his presidency while publicly attesting to his fitness during the re-election campaign.