The Carnegie Library in Pittsburgh recently suffered one of the greatest losses of all time after $8 million worth of books, maps, and plates were stolen. Now, two men have been charged with the theft of the materials after selling them to a rare books store.

According to the investigation that outed their scheme, Gregory Priore, the library’s archivist, and John Schulman, owner of Caliban Book Shop in Pittsburgh, had been working together since 1992. In 2017, a member of the library’s staff began auditing its Oliver Room, which houses some of the institution’s rarest items. In all, 336 items were determined to be missing or damaged beyond repair.

Later, 14 of the missing books, including as a signed first-edition copy of “De la France et des Etats-Unis” by Thomas Jefferson, were found for sale at Caliban. Schulman had allegedly sold the materials there and to several other vendors, while keeping some in a warehouse.

Priore’s original charges were pleaded down to theft of unlawful taking and receiving stolen property. Schulman pleaded guilty to charges of theft by deception and receiving stolen property.

Schulman’s attorney Albert Veverka has stated that his client would be “accepting responsibility for his association with books under circumstances whereby he should have known that the books had probably been stolen.”

The two men are scheduled for sentencing on April 17. They face potential jail time as well as fines and restitution.