What circumstantial evidence?
https://www.wsj.com/articles/the-world-needs-a-real-investig...
There's also been a string of academic preprints and articles, like
https://arxiv.org/ftp/arxiv/papers/2102/2102.03910.pdf
The authors tend to be kind of fringe, not surprisingly given the reputational cost (and given that if a lab origin is ever confirmed, many of the techniques that top researchers have spent their lives mastering will probably become illegal). A lot of very senior virologists are on the record as open to the possibility of a lab escape, though, for example:
> Baric said he still thought the virus came from bats in southern China, perhaps directly, or possibly via an intermediate host, although the smuggled pangolins, in his view, were a red herring. The disease evolved in humans over time without being noticed, he suspected, becoming gradually more infectious, and eventually a person carried it to Wuhan “and the pandemic took off.” Then he said, “Can you rule out a laboratory escape? The answer in this case is probably not.”
https://nymag.com/intelligencer/article/coronavirus-lab-esca...
I don't recommend that article in general; the author uses his talents as a novelist to paint a more vivid picture than I believe the evidence justifies. I do trust him to faithfully print the quote, though.
https://elifesciences.org/articles/31257
For the original SARS, it's palm civets, identified in less than a year. (The link to bats wasn't discovered until much later, by Shi Zhengli; but the intermediate host is enough to feel pretty confident it's natural-origin.)
For SARS-CoV-2, we're still waiting for that intermediate host. That's the significance of the early pangolin papers; but as Alina Chan and many others have noted, those papers have significant data quality issues, and even the Chinese have pretty much abandoned the pangolins.
And as your first article details, the "lab accident" theory rests on some lab doing secret virus experiments. Even if you find a whole sea of the virus in some cave, someone will argue they could have gotten there after the first "accident". Good luck disproving that without letting US virologists snoop in every lab in China.
To me "open to the possibility" is a very strong reading of "can't rule it out".
If we ever find the same for SARS-CoV-2, then I believe that pretty confidently excludes origin from lab manipulation (e.g., serial passaging). It would still be possible that the first human infected was on a WIV sampling trip, and not even all that unlikely (since an expert deliberately looking for novel viruses is far more likely to find them than e.g. a merely reckless wildlife trafficker).
If we see evidence in the phylogenetic tree of multiple animal-to-human spillover events--as we do for MERS--then that would pretty clearly exclude any scientific activity as the origin. At the very least, it would imply that even if some hapless grad student did accidentally start the pandemic, if they hadn't then someone else would have soon after. But as you say, so far we have neither.
Presumably someone in the Chinese government ordered Google to lie about the institute's location. Why would the Chinese government do that if the institute was uninvolved?
Investigators ought to ask China who ordered it, and why. And ask Google the same thing.
I do feel a bit sorry for Google employees who'd be caught in the middle if this actually happens.
US government to Google: "Tell us about how China ordered Google Maps to help with the coverup. If you lie to the investigators, we'll send you to jail."
China government to Google: "When the US asks about the Google Maps coverup, lie. If you don't lie to the investigators, we'll send you to jail."
Ralph Baric and 'batwoman' Shi Zhengli worked together on several coronavirus research projects spanning more than a decade.
It's like asking the fox if he knows where the hen went.