An important copy of Leonardo da Vinci’s famous “Salvator Mundi” painting is back in the hands of an Italian museum after being stolen at some point in the last year. No one knew it was missing.

Police found the copy, which shows Jesus with his right hand raised in a blessing and the left holding a crystal orb, in an apartment in Naples, according to CNN. Painted in the 1510s, possibly by one of da Vinci's students, the artwork replicates the most expensive painting in the world which has not been seen in public since a $450.3 million sale in 2017 (possibly to a representative of Saudi Crown Prince Mohammed Bin Salman, CNN reported).

The museum where this duplicate was kept, Museodoma San Domenico Maggiore, has been closed for months due to COVID-19 and no one had noticed it missing, The Guardian reported.

Related: 5 things you probably didn't know about Leonardo da Vinci

Some art historians have raised doubts that the original "Salvator Mundi" of which this stolen painting is a copy is authentic. As ArtNet News reported when the painting was auctioned off at Christie's in New York three years ago, the original had been lost for centuries. Art historians previously believed the work that sold for $450.3 million was the work of lesser-known artist Boltraffio before a consensus emerged in the 21st Century that it was the lost Leonardo "Salvator Mundi." Some researchers still doubt it is a true Leonardo. In either case, the copy appears to have been based on the $450.3 million painting

Like the stolen-and-recovered copy by a da Vinci student, the "original" depicts Jesus looking right at the viewer in a stolid pose. A more recently discovered sketch, reported on by ArtNet News, shows Jesus with his head turned to the side wearing a softer expression. Some have suggested this sketch outlined the true "Salvator Mundi," which would indicate the one sold in 2017 was not a Leonardo.

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In either case, the copy is now back in the Naples museum's possession after its brief jaunt as contraband. A 36-year-old owner of the apartment has been arrested, according to The Guardian, though it remains unclear how the piece was stolen.

"Whoever took the painting wanted it, and it is plausible that it was a commissioned theft by an organization working in the international art trade," said Naples prosecutor Giovanni Melillo, according to The Guardian.

Originally published on Live Science.