WASHINGTON — President Joe Biden’s former White House physician on Wednesday would not answer questions as part of the House Republican investigation into Biden’s health in office.

Dr. Kevin O’Connor invoked his rights under the Fifth Amendment during a closed-door interview with the House Oversight Committee, his attorney and lawmakers said.

Republicans on the Oversight Committee subpoenaed O’Connor last month as part of a their sweeping investigation into Biden’s health and his mental fitness as president. They claim some policies carried out during Biden’s term through the use of the White House autopen may be illegitimate if it’s proven the Democrat was mentally incapacitated for some of his term.

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

David Schertler, one of O’Connor’s lawyers, said the doctor had “no choice” but to invoke his Fifth Amendment rights in testimony before the committee. Schertler cited both O’Connor’s responsibilities to protect patient privacy as a doctor and the Justice Department’s ongoing investigation into Biden’s use of the autopen.

Rep. James Comer of Kentucky, the Oversight chair, said O’Connor’s refusal to testify made it “clear there was a conspiracy.”

Witnesses routinely invoke their Fifth Amendment rights in testimony to Congress. Allies of President Donald Trump, for example, invoked their rights when refusing to testify to the committee that investigated the Jan. 6, 2021, attack on the Capitol by a mob of his supporters.

Comer has sought testimony from nearly a dozen former Biden aides as he conducts his investigation, including former White House chiefs of staff Ron Klain and Jeff Zients; former senior advisers Mike Donilon and Anita Dunn; former deputy chief of staff Bruce Reed, former counselor to the president Steve Ricchetti; former deputy chief of staff Annie Tomasini; and a former assistant to the president, Ashley Williams.

He has also issued a subpoena for Anthony Bernal, the former chief of staff to former first lady Jill Biden.

Rep. Robert Garcia of California, the top Democrat on the Oversight panel, dismissed the GOP investigation as a waste of time.