An academic librarian’s lists of “predatory” journals and publishers on Sunday vanished from the internet without explanation. His business partners now say he was forced to shut down the website.

Jeffrey Beall, scholarly communications librarian at the University of Colorado at Denver, created the lists in 2008. They grew to include thousands of journals and publishers that Beall alleged exploit open-access publishing for their own profit -- for example by spamming researchers with invitations to publish their findings or present at conferences, then pocketing publication or registration fees while providing little or no quality review. Beall populated the lists based on 52 criteria he developed.

People first noticed Beall’s website had been wiped on Sunday. The pages that contained the lists now read, “This service is no longer available.” Since the content disappeared without notice, many suspected the website had been targeted by hackers or a lawsuit.

Lacey E. Earle, vice president of business development for Cabell’s International, said on Twitter Tuesday that Beall “was forced to shut down [the] blog due to threats and politics.” A spokesperson for the company said the information came from Beall, but that it was all he told them.

@CabellsPublish stands behind close personal friend @Jeffrey_Beall who was forced to shut down blog due to threats & politics #academicmafia — Lacey E. Earle (@lacey_earle) January 17, 2017

Beall declined to comment.

Cabell’s, which offers services that help librarians, researchers and others discover scholarly journals, has since 2015 worked with Beall on developing a journal blacklist. That list is slated to launch this spring. In response to speculation this weekend that the removal of Beall’s lists had anything to do with that initiative, however, Cabell’s said on Twitter that it “is in no way involved.”

Beall’s lists have been controversial among researchers and scholarly communications experts. Advocates of open-access publishing have criticized Beall for being overly negative toward the model. In a 2013 essay, for example, Beall wrote that the open-access movement is an “anti-corporatist, oppressive and negative movement, one that uses young researchers and researchers from developing countries as pawns.”

Some publishers have objected to being featured on the lists. OMICS International, a publisher Beall has previously described as “the worst of the worst,” in 2013 threatened to sue Beall, seeking $1 billion in damages.

But Beall has also received credit for highlighting a growing problem in the field of scholarly publishing. A 2015 study by researchers at the Hanken School of Economics in Finland found that “predatory” publishing skyrocketed between 2010 and 2014, during which the number of scholarly articles published in journals on Beall’s list increased nearly tenfold. Many academics also rely on the lists to determine if a journal or a publisher is legitimate. Some of Beall's fans are advocates of open access who believe it's important for scholars to be able to differentiate between legitimate and less legitimate publishers.

In a statement, a spokesperson for CU Denver said Beall made a “personal decision” to take down the website, adding that the university did not play a role in that decision.

“Jeffrey Beall, associate professor and librarian at the University of Colorado Denver, has decided to no longer maintain or publish his research or blog on open-access journals and ‘predatory publishers,’” the spokesperson said. “CU Denver supports and recognizes the important work Professor Beall has contributed to the field and to scholars worldwide. CU Denver also understands and respects his decision to take down his website scholarlyoa.com at this time. Professor Beall remains on the faculty at the university and will be pursuing new areas of research.”