The story was broken by the Oxford student newspaper, The Oxford Blue: EXCLUSIVE: Christ Church professor arrested over scandal of stolen papyrus. HT Brent Nongbri at the Variant Readings Blog.
According to the Oxford Blue article, Professor Obbink was arrested on 2 March. The only source they give is a quotation from the Thames Valley Police which does not mention a name. It does, however, mention the age of the man arrested and it refers to an investigation of "a report of theft of papyrus from the Sackler Library in Oxford." That man was released "under investigation." It is not clear to me whether the Guardian article has any information about the arrest independent of the Oxford Blue article.
I note the story for information. I have no independent knowledge about it. You can decide what to make of it.
Earlier PaleoJudaica posts on this convoluted scandal are here and links.
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