A 500-year-old painting has been discovered in a flat in Italy and returned to a museum - where staff were unaware it had even been stolen.
The copy of Salvator Mundi, which is believed to have been painted by Leonardo da Vinci, was found in a bedroom cupboard in Naples on Saturday.
This copy is thought to have been painted by one of da Vinci's students.
The 36-year-old owner of the flat was arrested on suspicion of receiving stolen goods, police said.
"The painting was found on Saturday thanks to a brilliant and diligent police operation," Naples prosecutor Giovanni Melillo told the AFP news agency.
The artwork is usually part of the Doma Museum collection at the San Domenico Maggiore church in the city.
But Mr Melillo said officials were not aware it had been stolen because "the room where the painting is kept has not been open for three months" due to the coronavirus pandemic.
It is not known when the artwork was taken as no one had reported it missing, but the museum said it was in its possession as recently as last January.
Police are now investigating the circumstances of the theft, but there was no sign of a break-in at the museum.
"It is plausible that it was a commissioned theft by an organisation working in the international art trade," Mr Melillo said.
It is not known who painted the artwork, but some experts believe Leonardo's student Giacomo Alibrandi may have done so in the early 1500s.
It shows Christ with one hand raised, with the other holding a glass sphere.
And to add to the mystery - whether or not the original painting is an authentic Leonardo da Vinci is disputed. Leonardo died in 1519 and there are fewer than 20 of his paintings in existence.
The original Salvator Mundi has had major cosmetic surgery - its walnut panel base has been described as "worm-tunnelled" and at some point it seems to have been split in half. Efforts to restore it have also resulted in abrasions.
This did not detract buyers, however, and the painting became the most expensive ever sold when it was auctioned for a record $450m (£341m) in 2017.
The unidentified buyer was involved in a bidding contest, via telephone, that lasted nearly 20 minutes.