More than six years later, there is still no “smoking gun” proof for either of the two prevailing hypotheses of Covid-19’s origins, that SARS-CoV-2 emerged from a laboratory accident at the Wuhan Institute of Virology or from a natural jump from an infected animal. Nor is there direct evidence linking Fauci, or research at the WIV that NIAID funded while he was director, to the pandemic.

In the last few months, however, a release of new documents, some partly declassified by the Office of the Director of National Intelligence under Tulsi Gabbard, and some obtained by Senator Paul’s committee through subpoenas, show that, even as leading scientists and certain government officials, including Fauci, publicly argued against a lab leak, in private, at various times, they deemed it credible and even equally likely.

Their assessment came in part due to unusual features of the virus. Those include a furin cleavage site, a distinctive segment of SARS-CoV-2’s genetic code that makes the virus more infectious by allowing it to more efficiently enter human cells, raising the question of whether the virus was engineered.

Since 2023, both the Department of Energy and the CIA have shifted their assessments towards a lab leak as the likelier origin, joining the FBI, which was the first intelligence agency to assess with moderate confidence that SARS-CoV-2 originated from a laboratory accident. Four intelligence agencies, along with the National Intelligence Council, assess a natural origin for Covid-19.

One thing that also clearly emerges from the documents: as the world was engulfed by crisis, and the American public needed transparency, the effort by Fauci and scientists allied with him to obscure or downplay the U.S. government’s entanglement with the Wuhan Institute of Virology likely weakened America’s ability to pressure China to release more information.

On January 26, 2020, as the virus was emerging, Fauci wrote in his journal, “Now we know the [Huanan seafood] market was not the source, it was the amplifier. Having said that, somewhere the virus jumped from animals to humans.” The scientists allied with him would later argue that the market was the pandemic’s origin, serving as the spot where the virus first leapt from an infected animal to humans. (No infected animal has ever been identified.)

In his diary, Fauci then mentions a February 1, 2020 conference call, one that later became the subject of intense scrutiny. He had gathered top virologists to discuss the origin of the virus. His entry makes clear that the majority on the call “felt that deliberate insertion” of a furin cleavage site “was possible” due to the type of risky research the WIV had been pursuing. “We could not let this go.”

Yet by March of 2020, they had let it go. Four of the scientists on the call, all of whom had raised concerns about a lab leak, and a fifth author, published a scientific letter in Nature Medicine, “The proximal origin of SARS-CoV-2,” asserting that “any type of lab-based scenario wasn’t plausible.”

Emails obtained through freedom of information later showed that Fauci had worked behind the scenes to help shape the publication. But at the time, his role in the letter was not publicly known.

On April 17, 2020, at the White House podium, Fauci fielded a question from a reporter: Could SARS-CoV-2 have come from a lab? He responded that a recently published analysis from a “group of highly qualified evolutionary virologists” had concluded that the virus was “totally consistent with a jump of a species from an animal to a human.”

That positioning of the Proximal Origins letter played a significant role in relegating even factual questions about the possibility of a laboratory accident to the conspiracy-theory dustbin. To this day, there remain unanswered questions about what led the scientists involved to shift their assessments between the February 1 call and the publication of their lab-leak disavowal some six weeks later.

“These guys were messaging each other about how the virus looked like it was engineered and then after speaking with Fauci, switched gears quickly and published the Proximal Origins letter,” Jason Bannan, the FBI scientist who led the Bureau’s investigation into Covid-19’s origin, tells Rolling Stone. Meanwhile, he says, “Fauci was advising [the intelligence community] to listen to those experts, so he continued to promote them.”

In May 2020, one month after Fauci touted the Proximal Origins paper and its conclusion of a natural origin from the White House podium, the Z division of the Lawrence Livermore National Laboratory — an elite group of federal government scientists who advise the intelligence community — issued a classified report which argued that an accidental lab leak was equally possible.