A top aide to former first lady Jill Biden refused to answer GOP investigators’ questions on Wednesday as the House Oversight Committee probes whether senior ex-White House aides covered up signs of former President Joe Biden’s mental decline.

Anthony Bernal, former assistant to the president and senior advisor to the first lady, was compelled for a July 16 closed-door deposition after missing a previously agreed-upon interview date late last month.

His scheduled sit-down came and went quickly, however. Bernal apparently pleaded the Fifth Amendment to the questions asked by House staffers, a source familiar told Fox News Digital.

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House Oversight Committee Chair James Comer, R-Ky., is investigating allegations that Biden’s former top White House aides covered up signs of his mental and physical decline while in office, and whether any executive actions were commissioned via autopen without the president’s full knowledge. Biden allies have pushed back against those claims.

In an interview with The New York Times on Thursday, Biden affirmed he “made every decision” on his own.

“Original Sin,” a book by CNN anchor Jake Tapper and Axios political correspondent Alex Thompson, positions Bernal as a fiercely protective aide who was dubbed the leader of the “loyalty police” by other former Biden staffers.

His LinkedIn page lists him as currently working as Jill Biden’s chief of staff in the Transition Office of Former President Joe Biden.

Bernal was originally slated to appear last month for a voluntary transcribed interview, but he and his lawyers backtracked after the Trump administration announced it was waiving executive privilege rights for him and several other former White House staffers.

“Now that the White House has waived executive privilege, it’s abundantly clear that Anthony Bernal – Jill Biden’s so-called ‘work husband’ – never intended to be transparent about Joe Biden’s cognitive decline and the ensuing cover-up,” Comer said in late June.

He’s now the second former Biden administration staffer to invoke the Fifth Amendment after ex-White House physician Kevin O’Connor did so last week.

O’Connor’s deposition lasted less than 30 minutes, with the doctor refusing to answer any questions after his name.

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But O’Connor’s lawyers argued at the time that it was not an admission of guilt. Rather, they were concerned the scope of the committee’s questioning could force him to violate patient-doctor confidentiality, risking his standing as a physician.

A House Oversight Committee aide pushed back: “Doctor-patient objection would have meant he would have stayed and answered questions that didn’t implicate such privilege. Instead, he took the Fifth to all and any potential questions.”

Two other former Biden White House staffers appeared for voluntary transcribed interviews already.

Another, former deputy Chief of Staff Annie Tomasini, was also subpoenaed to appear this Friday.