The origin of the year-long coronavirus pandemic remains a mystery after scientists from the World Health Organization (WHO) wrapped up its investigation in Wuhan, China -- drawing criticism from U.S. officials.

Peter Ben Embarek, who led the months-long investigation with a team of WHO scientists, said Wednesday that the investigation did not drastically change the picture of the virus. But he did stomp on a theory that the virus escaped from the Wuhan Institute of Virology, a lab in China’s Hubei province.

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Embarek said the theory was "extremely unlikely" and did not require additional study.

"I think the report is shameful," Sen. Ted Cruz, R-Texas, told Fox News Wednesday, rejecting the conclusion that the virus did not in fact come from a lab. "The WHO, instead of stepping in as medical professionals, instead of acting quickly to stop this pandemic ... just echoed the lies from the Chinese Communist government."

Cruz pointed to the arrests of whistleblowers and scientists by the Chinese Communist Party (CCP) in late 2019 as examples of their attempts to cover-up the impending pandemic.  He further alleged the WHO helped the Chinese government hide the extent of its involvement in the coronavirus pandemic.

The Texas Republican maintains the belief that the virus was a mishap by the Chinese government, as the virus started "400 yards" from one of Wuhan’s labs, which he said happened to be studying a genetic sample of the coronavirus found in bats.

But the WHO team said they found no evidence that the novel coronavirus was being studied in the Wuhan lab prior to the outbreak.

Head of the COVID-19 panel at China's National Health Commission, Dr. Liang Wannian, also pointed to evidence that suggests the virus was prevalent prior to the first reported case, by "several weeks."

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"This suggests that we cannot rule out that it was circulating in other regions and the circulation was unreported," he said.

But WHO officials believe it is unlikely that the virus was transmitted directly from bats to humans, and that instead the virus hopped species through intermediary hosts like pangolins, ferrets, minks, snakes, or turtles.

Embarek said the WHO team of investigators found frozen wild animals being sold in the Wuhan market that came from regions where bats and hosts are known to carry a virus similar to novel coronavirus.

"We know the virus can survive in conditions that are found in these cold, frozen environments, but we don’t really understand if the virus can transmit to humans," Embarek said during the conference.

China has pushed the idea that the virus is being transmitted globally through frozen foods, claiming to have found traces of it on frozen shrimp from Saudi Arabia, beef from Brazil and pork from the U.S. – but experts have not proven that humans can then become infected.

COVID-19 "did not start in central China’s Wuhan but may come through imported frozen food and packaging: experts," the CCP said in a November Facebook post, reported Reuters last year.

But U.S. officials in the food and drug industry are saying, "not so fast" and pushed back on the suggestion that frozen foods could be the carrier of COVID-19.

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"There is no credible evidence of food, food containers, or food packaging being associated with or a likely source of transmission of [COVID-19]," Frank Yiannas, Deputy Commissioner for Food Policy and Response at the FDA said in a tweet Tuesday. "This particular coronavirus causes respiratory illness and is spread from person-to-person, unlike foodborne gastrointestinal or GI viruses, such as norovirus and hepatitis A that often make people ill through contaminated food."

The WHO investigative team has attempted to reign in expectations and pointed to the fact that it could take years for health experts to understand the origins of the coronavirus.