() President Joe Biden’s White House physician invoked his Fifth Amendment right and left a closed-door deposition on Capitol Hill shortly after arriving for questioning.

Some had questioned whether Dr. Kevin O’Connor would be able to answer questions he might face due to doctor-patient confidentiality, as Republicans have pushed for him to testify.

O’Connor was set to face questions about Biden’s age, health and mental state amid accusations that those in the former president’s inner circle had worked to cover up his cognitive state.

Biden has called the investigation ridiculous, while Republican lawmakers have continued to seek clarity.

Major areas of interest include Biden’s mental health and his recent diagnosis of aggressive prostate cancer, including questions about whether he was screened during his time in the White House.