Anthony Fauci and Sen. Rand Paul, R-Ky. clashed in a Senate hearing on Tuesday over whether the National Institutes of Health funded the controversial research in Wuhan, China that led to the coronavirus pandemic.

During the Senate Committee hearing about the government’s response to COVID-19, Paul criticized Fauci concerning the NIH-funded study, saying the NIH funded illegal gain of function research in the Wuhan Institute of Virology that created the deadly and transmittable virus. This is an accusation Paul has made before, and Fauci has denied it. Paul accused Fauci of lying to congress. Fauci fired back saying “I have not lied before Congress. I have never lied, certainly not before Congress. Case closed.”

Paul then cited an academic paper that purportedly shows the lab had conducted illegal research to create “potential pandemic pathogens” that only exist in the lab. Fauci denied this claim.

“You do not know what you are talking about,” said Fauci as he scolded the Kentucky Senator.

Paul countered “no one is saying those viruses caused the pandemic. What we’re alleging here is that the gain of function research was done in the lab and NIH funded it. You can’t get away from it, it meets your definition and you are obfuscating the truth,” Paul said.

The NIH did fund a non-profit called the EcoHealth Alliance that researched bat coronavirus at the lab in Wuhan. Fauci maintains that experts examined the study “up and down” and concluded it does not constitute gain of function research.

“How can you say that’s not a gain of function? It’s a dance and you’re dancing around this because you’re trying to obscure responsibility for 4 million people dying around the world from a pandemic,” Paul barked.

Fauci later interjected that Paul was the one obfuscating the truth, saying “You are implying that what we did resulted in the deaths of individuals. I resent that, and if anyone is lying here, senator it is you,” he said.

The Wuhan Institute of Virology has been under investigation by the World Health Organization since the beginning of the pandemic. The WHO has also called for further cooperation from the Chinese government and announced that the agency was denied the raw data needed for a more complete probe.

Tedros Adhanom Ghebreyesus, director of the WHO is asking “China to be transparent and cooperative” on the information that was asked for during the early days of the pandemic.

Investigations into how the pandemic began are still being conducted by the U.S. government. President Biden set a deadline for late August for the intelligence community to report back to him on the origins of the pandemic.