At a highly anticipated Senate hearing, Anthony Fauci on Wednesday invoked his Fifth Amendment right to refuse to answer questions about the Covid-19 pandemic and its origins, saying he was doing so on the advice of his attorneys.

The former U.S. health official, who achieved rock star status for a time due to his central role in charting the U.S. response to the pandemic, had been subpoenaed to testify before the Senate Homeland Security and Governmental Affairs Committee, a panel headed by Sen. Rand Paul (R-Ky.), who had made no secret of his desire to see Fauci behind bars. Among other allegations, Paul has accused Fauci of covering up the origins of the virus that causes Covid — which the senator believes was caused by a lab leak in China — and lying to Congress.

Before stating that he would not answer questions, Fauci noted that in his nearly four decades as director of the National Institute of Allergy and Infectious Diseases he had testified before or briefed House and Senate committees more than 200 times — a track record, he said, that demonstrated his belief in and respect for “legitimate congressional oversight.”

Fauci said that it pained him to invoke his Fifth Amendment rights, but said he was doing it because it seemed clear “that the sole reason [Paul] is calling me before this committee is to get me to say something that could vindicate his repeated public pledges that I end up, in his words, ‘behind bars.’”