Spanish police have arrested seven people suspected of involvement in the theft of five paintings last year worth $38.7 million by renowned British artist Francis Bacon.
The paintings were reported stolen in July 2015, along with a safe containing coin collections and jewellery and have yet to be recovered.
Spanish detectives were approached in February by British private investigators specialising in the recovery of stolen artworks who had received an email with photographs of the stolen works asking if they were listed as stolen, national police said in a statement.
Investigators then analysed the photographs and were able to determine that the camera that took the images was owned by a photographic equipment rental company.
The firm then supplied the details of the customer who had rented it at the time the paintings were photographed.
The customer was among those arrested, along with a Madrid art dealer and his son.
Sources close to the investigation said in March that the theft appeared to have been a highly professional operation, which took place while the owner was away in London with the perpetrators disabling the alarm system.
The owner of the paintings was reportedly a close friend of Bacon.
Irish-born Bacon died in Madrid in 1992, aged 82, and his expressionist-surrealist works, which are often raw and emotional, remain highly sought after.
Bacon’s death only enhanced his reputation, and the 2013 sale of his 1969 work Three Studies of Lucien Freud fetched more than $198 million at auction — a world record at the time.
Art market information leader Artprice lists Bacon as one of 10 frontline modern artists alongside Picasso and Andy Warhol.