In July 2013, robbers nimbly stole 10 paintings and two drawings in the course of two minutes from the Van Buuren Museum, located on the outskirts of Brussels.

Several of the works stolen are said to be of great value, including The Thinker (1907) by Dutch painter Kees van Dongen, estimated at a replacement value of €1.2 million.

Other works stolen included a painting by Pieter Brueghel the Younger, and James Ensor’s Shrimps and Shells (1894). The thieves also nabbed a drawing titled Peasant Woman Pealing Potatoes that, although labelled as a Vincent van Gogh, is believed to be a fake.

Now, two years after the heist, the Van Buuren Museum is negotiating with the thieves to get its art back after paying a ransom, TV Brussels reports.

“It’s a choice we have to make between two evils,” said art expert Jacques Lust in an interview with TV Brussels. “Not negotiating would mean […] having little chance to see the artworks again one day.”

On the other hand, “having contact with the robbers can lead to a solution—if we can come up with the money to pay them,” he claimed.

The museum and the police cannot give out details concerning the case. But one thing is certain: Artnapping—the stealing of art for ransom—has reportedly gained popularity in the criminal world.

“It happens more and more,” Lust explained. “Not all details make it to the media, of course. If a case is solved there’s no mention of the amounts paid, nor of the works having been stolen. But there’s been an increase in such cases,” he said.