Anne Onymous, the YouTube user who anonymously circulated the now-infamous video of Mitt Romney speaking at a private fundraiser, now appears to be threatening to release the Republican candidate's tax returns.

Here's a tweet, sent Tuesday afternoon by a user with the handle AnneOnymous670:

Very little is known about the source who leaked the video of Romney's fundraiser, so the credibility of the new threat is unclear.

Here's what we do know:

On May 17, Romney spoke with donors at a private fundraiser in Boca Raton, Fla., hosted by private equity executive Marc Leder.

A clip, reportedly from the fundraiser, surfaced online three months ago, featuring Romney describing the working conditions at a factory he visited in China during his years at Bain Capital. The clip, posted by a user named Rachel Maddow, was taken down because the user was not the MSNBC host. It was reposted by another user, RomneyExposed, along with three other clips from the fundraiser. On June 10, a commenter named RomneyExposed started promoting the clips on the Huffington Post.

Three weeks ago, six additional clips were posted on YouTube by the user Anne Onymous. A Twitter user by the same name started tweeting out the YouTube links on August 28, reaching out via Twitter to Mother Jones reporter David Corn, Democratic strategist Donna Brazile, Democratic National Chairwoman Debbie Wasserman Shultz, Obama's campaign press secretary Ben LaBolt and northeast regional press secretary Michael Czin, ABC reporter Emily Friedman, and union leader Steven Tolman, president of the Massachusetts AFL-CIO.

A Twitter user by the same name started tweeting out the YouTube links on August 28, reaching out via Twitter to Mother Jones reporter David Corn, Democratic strategist Donna Brazile, Democratic National Chairwoman Debbie Wasserman Shultz, Obama's campaign press secretary Ben LaBolt and northeast regional press secretary Michael Czin, ABC reporter Emily Friedman, and union leader Steven Tolman, president of the Massachusetts AFL-CIO. The Huffington Post and James Carter, a Democratic opposition researcher who also happens to be former President Jimmy Carter's grandson, reached out to the source of the videos. Carter subsequently connected the source of the videos with David Corn of Mother Jones.

Anne Onymous appears to be primarily concerned with the clip of Romney talking about his visit to the Chinese factory. A Google + page for the user Anne Onymous, which uses the same picture as the YouTube channel and the Twitter user, describes the user as living in Dongguan, China, and working at Global Tech Appliances, Inc., the company that owns the factory Romney is reported to have visited.

Here's the Google + About Me page:





Interestingly, the full video posted Tuesday, which Mother Jones claims has not been edited, does not contain the clip of Romney discussing his visit to the factory in China.