Three suspected members of an art forgery ring were arrested in the Spanish cities of Zaragoza and Tarragona, El Pais reported. Accused of peddling drawings falsely attributed to Miró, Picasso, and Matisse, they’ve been charged with crimes against intellectual property and fraud.

The police first caught whiff of their dealings in July 2014, during a routine check on the border of Spain and Andorra. Inside the car of an Andorran resident they found drawings signed by Miró. Though the man was carrying documents attesting to their authenticity, police decided to go ahead and have them inspected by several experts. All confirmed that the drawings were counterfeit.

The man was then placed under surveillance by the Historical Heritage Group of the Civil Guard for an operation called “Mirones.” He was observed traveling frequently from Andorra to Zaragoza, where he would meet with gallery owners and collectors. He would often deposit fake artworks in the office of a lawyer in Tarragona, so as to avoid the possibility of them being intercepted at the border.

“Once we collected and processed all the information, we proceeded to the operational phase of the operation, arresting this person and charging two others, including a gallery of art from Zaragoza that allegedly collaborated as an intermediary for the sale of the forgeries,” the police explained in a press release.

Over the course of the investigation, they discovered nine counterfeit paintings: six attributed to Miró, two to Matisse, and one to Picasso that came with a false certificate of authenticity. The arrest thwarted the sale of two lithographs the suspects were trying to pass off as works by Miró.

This is the second time in less than a year that Spain has made art-forgery-related arrests within its borders. In April 2014, authorities arrested Spanish art dealer Jose Carlos Bergantinos Diaz, who, along with his partner, Glarifa Rosales, has been accused of selling more than $30 million worth of fake art attributed to the likes of Warhol and de Kooning. The works were forged in Queens, New York, then sold at Knoedler & Co. gallery for a total of more than $80 million.