(NewsNation) — Anthony Fauci, former chief White House medical adviser, is expected to testify before Congress this week as part of Republicans’ yearslong investigation into the origins of COVID-19 and the U.S. response to the disease, sources confirmed to NewsNation. Fauci was seen entering the Capitol on Monday morning.

The House Select Subcommittee on the Coronavirus Pandemic said the two day closed-door, transcribed interview will take place on Jan. 8 and 9. Fauci will face questions on the origins of COVID-19, vaccine mandates and how to prevent something like the COVID-19 pandemic from happening again. It will be Fauci’s first appearance before the Republican-controlled House.

Fauci, who served as the nation’s top infectious disease expert before retiring at the end of 2022, will also testify in front of the panel later this year, with the date still to be determined.

Subcommittee Chair Brad Wenstrup, R-Ohio, told The Hill this interview will serve as an “after action review” of the federal government’s actions during the public health emergency for COVID-19.

“I think Dr. Fauci’s testimony is really a crucial component of the work we’re trying to do as it relates to the origins of COVID, the effects of mandates for vaccination, gain-of-function type research, scientific censorship in areas where it looks like it occurred,” Wenstrup said.

The committee first requested a sit-down with Fauci in February 2023, but an agreement over the timing and details of the interviews was just reached with Fauci’s attorneys earlier this month, according to a letter they sent in November.

House Republicans have investigated whether Fauci or other U.S. government officials took part in any sort of cover-up about the origin of the deadly virus. Fauci, who served under both Republican and Democratic presidents, has repeatedly called the GOP criticism “nonsense.”

Wenstrup, who is also a longtime member of the House Intelligence Committee, has accused Fauci and U.S. intelligence of withholding key facts about its investigation into the coronavirus. Republicans on the committee last year issued a staff report arguing there are “indications” that the virus may have been developed as a bioweapon inside China’s Wuhan Institute of Virology.

That would contradict a U.S. intelligence community assessment released in unclassified form in August 2021 that said analysts do not believe the virus was a bioweapon, though it may have leaked in a lab accident.

Many scientists, including Fauci, say they still believe the virus most likely emerged in nature and jumped from animals to humans, a well-documented phenomenon known as a spillover event. Virus researchers have not publicly identified any key new scientific evidence that might make the lab-leak hypothesis more likely.

But Republicans have accused Fauci of lying to Congress when he denied in May 2022 that the National Institutes of Health funded “gain of function” research — the practice of enhancing a virus in a lab to study its potential impact in the real world — at a virology lab in Wuhan. Sen. Ted Cruz, R-Texas, even urged Attorney General Merrick Garland to appoint a special prosecutor to investigate Fauci’s statements.

The Associated Press and The Hill contributed to this report.