Seven people have been arrested in Spain on suspicion of involvement in the theft of five paintings by Francis Bacon, worth a total of €25m (£19m).
The paintings were stolen last July, along with other valuables belonging to the owner, who is reported to have been a close friend of Bacon. The works, which comprise portraits and landscapes, are yet to be recovered.
Detectives said they were approached in February by British private investigators specialising in the recovery of stolen artworks who had received an email with photographs of the paintings and asking whether they were listed as stolen.
Investigators analysed the photo and were able to determine that the camera that took the images was owned by a photographic equipment rental company, which supplied details of the customer who had rented it at the time the paintings were photographed.