Macedonia’s National Museum has been systematically looted by its own director and a ring of six other accomplices for years. The Criminal Court in Skopje has found the seven guilty of theft of valuable artifacts and sentenced them to a total of 31 years in jail.

Former museum director Pero Josifovski received the longest sentence of nearly nine years for abuse of official position and illegal appropriation of cultural heritage.

The ring of illegal traffickers also included the museum’s programming director Zlatko Videvski, four other museums employees, and a jeweler.

The seven were charged with illegal appropriation of valuable cultural heritage owned by the state, malpractice, and abuse of official position, resulting in the artifacts’ theft by unknown individuals. Some were charged with failure to obtain proof over the origin of museum coins they had purchased from the jeweler.

The disappearance of 162 valuable artifacts from the museum was first registered in November of 2013.

The stolen objects come from the archeological site of Isar Marvinci, in the South East of Macedonia. A hundred and twenty one of them are made of pure gold and date from the classical era.

Isar Marvinci isn’t the only archeological site under threat in the country. Marivo, Vrance, and Cepigovo are also believed to be at risk of being plundered by thieves.

According to Ahram Online, an estimated 20,000 religious and cultural artifacts—some worth hundreds of thousands of euros—have been stolen in Macedonia over the last four years.

Several art heists around the world have recently been exposed as inside jobs (see Librarian Steals Priceless Documents from Russian Museum, $250 Million Turkish Museum Heist Was an Inside Job, Bronze Statues Recovered 32 Years After ‘Broad Daylight’ Theft in New York, Thieves Blackmail Vatican Over Return of Michelangelo Documents Stolen 20 Years Ago).