Geert Jan Jansen

He befriended a US art dealer, Michel Podulke [sv], who ran a gallery called Mokum in Amsterdam.

When his business went badly, he decided to sign posters of Karel Appel's lithographs and sell them as originals.

Short of evidence, the attorney general cut a deal with Jansen: He would not be charged if he would not make forgeries for three years.

In March 1994, "Jan van den Bergen" came to the auction house Karl & Faber in Munich.

Jan Nieuwenhuizen Segaar, a representative of Karel Appel, contacted the artist who said that the work was his but Cubitt was still suspicious.

Sue Cubitt decided to inform Ernst Schöller of the Stuttgart Fine Art and Antiquities squad.

The trail of false addresses companies led Schöller and the French police to a farm in La Chaux near Poitiers.

Forged artists included Cocteau, Dufy, Ferdinand Erfmann [nl], Charles Eyck, Leo Gestel, Bart van der Leck, Matisse, Miró and the most popular target of forgery, Picasso.

Six years later, they checked the auction records of a Drouot gallery where Jansen had traded most of his forgeries through a number of different false names.

They confiscated some suspicious paintings and threatened their buyers with complicity in the crime if they did not press charges against Jansen.