By Hilary Whiteman
(CNN) -- A smudged fingerprint has convinced art experts that a painting thought to have dated back to the early 19th century is the work of revered Italian artist Leonardo da Vinci.
Little is known of the painting before it appeared in an illustrated Christie's catalogue in the late 1990s labeled as "German, 19th Century" under the name of "Young Girl in Profile in Renaissance Dress."
It sold for $19,000 at the auction to respected New York art dealer Kate Ganz who kept it for 12 years before selling it on for a similar price in 2007. The work is now locked in a Swiss bank vault with an estimated value of more than $160 million.
Peter Silverman had seen the work during the original auction back in the 1990s. "I was actually an under-bidder because I thought it was a wonderful thing but I didn't have the knowledge at that time to go all the way," he told CNN.
More than 10 years later, he was walking in New York with a Swiss friend whom he describes as a "major collector of contemporary art."
"He popped into the Ganz gallery and saw this thing on her desk which was for sale. And he came out and said, 'Peter I don't know what I'm looking at here; I'm a contemporary collector. But I certainly would like you to have a look at it because it doesn't look 19th Century to me.' So I went and looked at it and I bought it right way for him."
Silverman then began the long process of proving that every expert and art lover who had seen the painting over the past decade -- and earlier -- had been wrong to assume that it was the work of anyone other than one of the world's greatest artists.