(WASHINGTON) — On the heels of a federal agency’s new assessment that COVID-19 “mostly likely” emerged from a lab leak rather than natural human exposure, a special panel formed by House Republicans to investigate the origins of the virus will hold its first hearing on Wednesday.

The House Select Subcommittee on the Coronavirus Pandemic, chaired by Ohio Republican Brad Wenstrup, will meet at 9 a.m. ET to tackle a question that’s plagued intelligence and health officials for the past three years: Where did the virus that has killed more than one million Americans and nearly seven million people worldwide come from?

The two prevailing theories are a leak from a laboratory in China, which the Chinese government vehemently disputes, or humans being exposed to an infected animal.

U.S. agencies have said they remain “divided” on the matter and with no “smoking gun” and limited access to raw data, including via cooperation from China, discussion of the science has played out in a haze of circumstantial evidence.

Witnesses at Wednesday’s hearing will include Dr. Robert Redfield, the Trump-era director of the Centers for Disease Control and Prevention, and Dr. Paul Auwaerter, a professor of medicine at the Johns Hopkins University School of Medicine.

“The American people deserve real answers after years of suffering through the Coronavirus pandemic and related government policies,” Wenstrup said in a statement. “This investigation must begin with where and how this virus came about so that we can attempt to ‘predict, prepare, protect, or prevent’ it from happening again.”

Jamie Metzl, a former adviser to the World Health Organization and former national security official in the Clinton administration, will also appear before the panel. According to a copy of his prepared testimony reviewed by ABC News, Metzl will say that “understanding how this pandemic began is essential to prioritizing our response” going forward and will help gear future oversight and attention to new threats.

“If, for example, we knew for certain the pandemic stems from a lab incident in Wuhan [in China], I can assure you that efforts to regulate the rapid proliferation of high-containment, and all too often high-risk, virology labs across the globe would get a massive boost,” Metzl plans to say. “Critically important biosafety efforts would finally get the high-level national and international attention they deserve.”

“Understanding how this crisis began and determining how we can do better is and must be the ultimate bipartisan and nonpartisan issue,” Metzl will say while urging pressure on and “demanding accountability from” Beijing.

“Doing so is not a hostile act, but the opposite,” Metzl will say. “Supporting and joining a full and unfettered investigation has always been the best way for the Chinese government to demonstrate its commitment to understanding what went wrong.”

Chinese Foreign Ministry Spokesperson Zhao Lijian previously said in a statement, “Origins tracing is a matter of science. China always supports and will continue to participate in the science-based origins study.”

According to reporting in The Wall Street Journal last week, the U.S. Energy Department, which oversees a network of labs, said it now believes COVID-19 “most likely” was the result of a leak from a lab — an assessment in line with that of the FBI.

“The FBI has for quite some time now assessed that the origins of the pandemic are most likely a potential lab incident in Wuhan,” FBI Director Chris Wray said in response to the Energy Department’s evaluation, which the Journal wrote was made with “low confidence,” citing people who read the report.

Four other U.S. agencies, however, believe the virus was a result of natural transmission and that it jumped from animals to humans at a wet market. Two other agencies are undecided as to how it started.

“There’s just no consensus across the government. The work continues,” White House spokesperson John Kirby told reporters last week.

While no firm conclusion has been made as to where exactly the virus originated, none of the findings so far indicate it was leaked intentionally.

Experts have said that, regardless of the number of hearings, successful investigation of COVID-19’s origins will almost certainly require fuller cooperation from the Chinese government. Looking into how outbreaks began takes extensive, on-the-ground scientific work.

Congressional Republicans have set their sights on investigating the origins of the virus, with House Republicans launching a probe not long after taking back majority control of the chamber.

A group of GOP senators are also now demanding to see the individual assessments on COVID-19 origins from each of the U.S. agencies.

“Congress should be able to review the independent evaluations without filters, ambiguity or interpretations of the intelligence,” a group of Republican senators, led by Kansas’ Roger Marshall, wrote in a letter sent Monday to Director of National Intelligence Avril Haines, who is set to separately appear this week before members of Congress’ intelligence committees.

“The ODNI has failed to be transparent with Congress and the American people by standardizing agency conclusions and thereby ignoring the breadth of scientific and other expertise in each agency,” the senators wrote.

Copyright © 2023, ABC Audio. All rights reserved.