The Hermitage Museum in St Petersburg, Russia announced on Monday that a member of its staff has been arrested on suspicion of stealing priceless books and documents—some hundreds of years old—from the institution’s archives, AFP reports.

The librarian, who tried to sell the stolen goods to antiquarian book dealers, was seized following an investigation launched when some items were reported missing during a routine inspection last month.

According to a statement issued by the FSB, Russia’s secret service, the items which were stolen from the museum included “Several engravings, lithographs, photographs and books dating from the 17^th to 19^th centuries.” The missing items were traced back to the employee’s home, the residence of the employee’s friend, and a St Petersburg antique shop. The items have since been recovered and returned to the Hermitage Museum.

The museum has encountered similar incidents in the past. In 2006 a curator helped her husband steal over 200 pieces of jewelry worth $4.5 million from the museum’s collection. The man was sentenced to five years behind bars. In 2010 a major investigation ordered by the Russian ministry of culture found that almost 250,000 artifacts have gone missing from Russian’s museums, most were presumed to have been lost or stolen.

Housed in the Winter Palace, the former home to the Russian Tsars, the Hermitage Museum is one of the most popular cultural destinations in Russia welcoming roughly 2 million visitors annually.