House Oversight and Government Reform Committee Chair James Comer (R-Ky.) issued a subpoena on Thursday for testimony from former President Biden’s White House doctor, Kevin O’Connor.

It’s Comer’s latest move to expand his panel’s probes into Biden’s mental acuity.

“Among other subjects, the Committee expressed its interest in whether your financial relationship with the Biden family affected your assessment of former President Biden’s physical and mental fitness to fulfill his duties as President,” Comer said in a letter accompanying the subpoena. “Given your connections with the Biden family, the Committee sought to understand if you contributed to an effort to hide former President Biden’s fitness to serve from the American people.”

The subpoena dictates that O’Connor appear for testimony at a deposition on June 27, and comes after O’Connor had declined Comer’s request to voluntarily appear before the committee.

O’Connor’s attorneys previously told the committee that the denial to appear was due in part to a D.C. code concerning physicians disclosing patient information to a court without consent, “ethical obligations pursuant to ‘Principal No. IV of the Code of Ethics of the American Medical Association (AMA),’” and “physician-patient privilege,” according to the letter from Comer.

“These arguments lack merit,” Comer wrote.

“Congress is not a court; this Section therefore in no way precludes you from appearing and testifying regarding your role as Physician to former President Biden,” the letter said.

O’Connor’s attorney David Schertler told The Hill in a statement: “We just received the correspondence and subpoena from the House Oversight Committee this afternoon. We will review it carefully and respond to Chairman Comer after we have had a chance to do so.”