Republican officials have launched a multi-pronged investigation into former President Joe Biden’s cognitive decline, seeking to discover whether White House officials covered it up and, if so, who was really running the country. However, a key witness has refused to answer questions in a congressional deposition. Kevin O’Connor, who served as Biden’s physician both when Biden was vice president and when he was president, appeared before the House Oversight Committee on Wednesday and refused to answer whether or not he was instructed to lie about the then-president’s health.

“On the advice of counsel, I must respectfully decline to answer based upon the physician-patient privilege and in reliance on my right under the Fifth Amendment of the Constitution. I am not a lawyer, and I must follow my lawyer’s advice in this matter,” O’Connor said in response to each question. He began by stating his name, when asked to, and answered, “Yes,” when asked if he swore to tell the truth while being sworn in. Afterward, he asserted doctor-patient privilege and cited the Fifth Amendment in response to every question.

Oversight Committee Chairman James Comer (R-Ky.) said in a social media post following the deposition, “It’s now clear there was a conspiracy to cover up President Biden’s cognitive decline after Dr. Kevin O’Connor, Biden’s physician and family business associate, refused to answer any questions and chose to hide behind the fifth amendment.” He continued, “The American people demand transparency, but Dr. O’Connor would rather conceal the truth. Dr. O’Connor took the fifth when asked if he was told to lie about President Biden’s health and whether he was fit to be President of the United States.” The congressman pledged that the Oversight Committee “will continue to interview more Biden White House aides to get the answers Americans deserve.”

President Donald Trump waived executive privilege so that O’Connor and other high-ranking Biden White House officials could testify before Congress concerning Biden’s cognitive decline and the Biden administration’s extensive use of the autopen, a subject that has raised questions about the legitimacy and constitutionality of many of Biden’s executive orders and actions. Late last month, former Biden advisor and staff secretary Neera Tanden testified before the Oversight Committee and reported that although she was “authorized” to use the then-president’s signature via autopen, she did not know whether Biden himself approved of specific executive orders and actions, leaving open the possibility that other senior Biden administration officials may have been making Biden’s decisions for him.

O’Connor’s attorneys informed the Oversight Committee on Wednesday that the physician would only respond to questions by asserting doctor-patient privilege and his Fifth Amendment rights. When asked whether O’Connor’s assertion of his Fifth Amendment rights, which protect an individual from providing testimony incriminating himself, instead of only citing doctor-patient privilege, was an attempt to avoid incriminating himself, O’Connor’s attorneys said that a “pending Department of Justice criminal investigation leaves Dr. O’Connor no choice but to invoke his constitutional rights under the Fifth Amendment.”

That investigation was launched by Trump himself, who tasked White House Counsel David Warrington and the Justice Department with determining whether the Biden administration conspired to cover up the then-president’s cognitive deterioration as well as “the circumstances surrounding Biden’s supposed execution of numerous executive actions during his final years in office,” with a focus on “the policy documents for which the autopen was used” and, crucially, “who directed that the President’s signature be affixed.”

In comments to The Washington Stand, Heritage Foundation Senior Legal Fellow Hans Von Spakovsky asserted, “If these public officials lied under oath to Congress, as has been alleged, then they should be investigated and prosecuted. Part of that investigation should include whether they corruptly used their official positions for political purposes to target individuals with improper law enforcement and intelligence operations.”

Von Spakovsky added, “Such misbehavior is not only illegal, but unacceptable in a democratic republic that depends on honest government officials carrying out their duties without betraying the public trust.”