LONDON — A trans-Atlantic investigation conducted by a Washington museum and a London-based archaeological group has accused a prominent Oxford University professor of stealing and selling fragments of ancient texts to Hobby Lobby, the arts-and-crafts chain.

The fragments come from the Oxyrhynchus Papyri, a prized collection of more than half a million pieces of papyrus and parchment dating from the third century B.C. to the seventh century A.D . discovered in Egypt by two archaeologists in the late 19th century. The collection is held at Oxford University and overseen by the Egypt Exploration Society of London.

Thirteen fragments from the collection were found in the Museum of the Bible, a Washington institution founded by Hobby Lobby’s evangelical Christian owners, the Green family. The Egypt Exploration Society began an investigation in June after a director of the Bible museum released a redacted copy of a 2013 contract between the professor, Dr. Dirk Obbink, and Hobby Lobby stores for the sale of six items, including four thought to be from the Oxyrhynchus collection.

The three-month investigation accused Professor Obbink, a member of Oxford University’s classics department, of taking a clutch of ancient fragments of the Bible without authorization and secretly selling them to Hobby Lobby in transactions from 2010 to 2013. In a statement released on Tuesday, the Egypt Exploration Society said that Mr. Obbink had sold 11 of the fragments that subsequently ended up at the Museum of the Bible.