When the police cleared Occupy Wall Street protesters from Zuccotti Park last November, the movement lost not only its central gathering spot, but also one of its more popular institutions: a collection of 3,600 donated books known as the People’s Library.

The fate of the books constitutes one of the enduring riddles accompanying the story of the two-month Occupy encampment of the park, in Lower Manhattan. As the group’s librarians sought to retrieve their property from the city, they were able to recover only about 1,000 books. Some 200 were badly damaged, the librarians said, adding that about 2,400 were not found.

In May, Occupy members sued New York City, saying that the seizure of the books violated their 1st, 4th and 14th Amendment rights and that they believed the missing books had been destroyed by the city.

Since then, the mystery surrounding the books has deepened. In June, the city suggested that Brookfield Office Properties, the owner of Zuccotti Park, may have been responsible for their seizure. Last month, Brookfield turned the blame back toward the city.