Conspiracy theorists need little more than suspicion, some cherry-picked facts and vibrant imaginations to spin tales about the origins of the COVID-19 pandemic. But for the scientists working to establish the facts, the path to the truth is much more plodding.

Their search will take them through a trove of medical records whose quotidian details will be important guideposts to the time and circumstances of the coronavirus's birth as a human pathogen. Patients' recall of their whereabouts and contacts will matter too.

But even if the Chinese government were willing to open all its patient files to international investigators — it currently is not — symptom reports and patients' memories can be fallible and confusing. Researchers need to check every fact as they ferret out the story, piece by piece.

University of Arizona evolutionary biologist Michael Worobey offers a down payment on such sleuthing in this week's edition of the journal Science.

Drawn from medical journal articles, the work of World Health Organization investigators, media reports and online accounts, Worobey's reconstruction leaves many questions unanswered. But it provides a road map for further investigation.

Worobey has played an influential role. He was one of 18 scientists whose objections to a WHO report on the coronavirus' origins reignited investigation into the possibility that it might have leaked from the Wuhan Institute of Virology.

Their letter was published in Science after the WHO declared it “likely to very likely” that the virus jumped to humans from animals, and “extremely unlikely” that it escaped from the government lab. Noting that the two theories “were not given balanced consideration,” the group called for “a proper investigation” to resolve the issue.

Worobey said at the time that “both” explanations “remain on the table for me.”

But his new work leans heavily to the “animal spillover” explanation.

Worobey's effort is meeting with mixed reviews.

“I don't think this advances in a major way our collective understanding of what really happened,” said Dr. David Relman, the Stanford microbiologist who organized the Science letter. Since Worobey's new narrative is constructed mainly of “third- and fourth-hand information,” it is fragmentary, inconsistent and potentially unreliable, Relman said.

But Scripps Institution microbiologist Kristian Andersen, who has long argued that an animal spillover was more likely than a lab leak, lauded Worobey's research for “uncovering several new key insights.”

The collective evidence “clearly points to the Huanan Market as a very likely source of the origin of the COVID-19 pandemic,” Andersen said.

Worobey's account calls into question the date and location of the earliest reported case of the mysterious type of pneumonia that was later recognized as COVID-19. His research suggests it was not — as has been widely reported — a 41-year-old accountant with no connection to the Huanan Market, but a seafood vendor who worked there. (A Chinese investigative reporter would discover that the accountant's Dec. 8 fever was due to an infection after dental surgery to remove retained baby teeth. The accountant would go on to develop another fever eight days later that was a sign of COVID-19.)