Some experts are still dubious, The Times of London reported. But Pietro Marani, who helped to restore Leonardo's "Last Supper" frescoes, said he believes the artist did the portrait and a later artist added to it.
Giancarlo Ligabue, the portrait's owner, said he was warned "Don't start thinking it's a Leonardo" when he bought the tiny drawing 30 years ago from an antique dealer. For almost three decades he followed that advice -- until Leonardo expert Luisi Cogliati Arano suggested he get scientific tests.
Infrared photography disclosed a preliminary sketch, something Cogliati Arano says is typical of Leonardo.
"There are several details that are similar to other portraits by Leonardo, including the hairstyle, the flower above it, the eye and the profile itself," she said.
The drawing is to be unveiled Thursday in Venice.
Megyn Kelly: Santa Claus and Jesus are both white men
Susan Sarandon: I was stoned at almost every awards show