Three of the seven people arrested so far in the investigation into the theft of Romanian gold treasures from the Drents Museum in Assen will not face charges, the public prosecution department said on Thursday.

Even though they did support the main suspect, it cannot be proven that they knew their actions were connected to the robbery, the department said in a statement. In addition, their role was too small to merit a court hearing.

The three main suspects remain in custody in Heerhugowaard and all will face charges of theft and damaging the museum itself by using a firework bomb to gain access.

Two of the three, aged 20 and 25, are also suspected of stealing the getaway car, which was later found burned out. The fourth of the minor suspects will face charges of stealing car number plates, the department said.

The next procedural hearing in the case will take place on October 16 and the full trial will be held in the first half of 2026.

The heist took place in the early hours of a Saturday morning in January after an explosion shattered windows and caused damage to the museum buildings.

The thieves made off with the golden helmet of Cotofenesti, crafted from almost pure gold and dating from 500 BC, along with three gold armbands.

The Romanian authorities have since criticised the Drents Museum for not having enough security measures in place. Camera footage of the heist shows three men breaking down the door following the explosion.

Neither the helmet or the armbands have yet been recovered.

Police sources told RTL Nieuws in May that the thieves were connected to the banned Hardliners biker gang. They believe they were instructed by Romanian underworld contacts who wanted to use the helmet as a bargaining chip to secure the release of gangsters from prison.