Police have arrested a fourth person in the hunt for robbers who stole valuable Romanian artefacts from the Drents Museum in Assen.

The man, a 26-year-old from Heerhugowaard, was apprehended in Obdam in Noord-Holland province early on Thursday. It is not clear what his relationship is with the two men and one woman who were arrested earlier in connection with the heist and who remain in custody.

He is currently being questioned by police about his role in the robbery. During a search at an address in Heerhugowaard, Noord-Holland, and a lock-up in Koggenland, police impounded two cars, devices, and clothing.

The search for another man, who was seen at a DIY store, is continuing.

The gang is accused of making off with some of Romania’s most treasured artifacts, including the golden helmet of Coțofenești, crafted from almost pure gold and dating from 500 BC, along with three gold armbands, all part of the country’s Dacian heritage.

A Dutch businessman living in Bucharest, Alex van Breemen, has put up a €250,000 reward for a so-called “golden tip” leading to the recovery of the items.

If they are not found, the Netherlands will have to stump up €5.8 million in compensation.