LONDON Oct. 14, 2009 -- It is a real-life art world mystery that began with a hunch that a painting holds a 500-year-old secret.
Until now, it was believed to be a non-descript German portrait from the 1800s. But one art dealer and a team of investigators suspected something more.
They saw in this small picture the hand of Leonardo da Vinci -- dubbed by many the greatest artist of all time, the man behind the "Mona Lisa," "Vitruvian Man" and "The Last Supper."
Canadian-born art collector Peter Silverman bought "Profile of the Bella Principessa" at the Ganz gallery in New York on behalf of an anonymous Swiss collector in 2007 for about $19,000.
"When I saw it my heart beat a million miles a minute. I thought of Leonardo, but I dared not pronounce the name" he told "Good Morning America" today.
Silverman began analysing the picture and a fingerprint was discovered in the top left corner of the painting.
A forensic art expert based at the Lumiere Technology laboratory in Paris then scanned the painting with a super-high-tech camera.
"With this technology, we go where nobody is able to investigate underneath and with top quality and cutting edge tool to research the truth. Is it or not a Leonardo or another one?" Pascal Cotte, a scientist involved with the project told ABC News.
The fingerprint, hidden under chalk and ink, was clearly discernible and on closer examination appeared to match one on another da Vinci painting of St. Jerome which hangs in the Vatican.
Experts believed they had found their man.
"I don't think it's necessary to go a step further [to verify it's a da Vinci] because if you want to explain to us this is not a da Vinci, you have to use a more powerful tool, and I'm sorry but until now it's impossible," Cotte says.
Continuing their detective work, investigators found other promising clues. The canvas, or vellum, was carbon-dated to 1440 to 1650, a match with the Da Vinci period. They also found that the artist who painted this was left-handed, a rarity among artists of this time and again a match with da Vinci.
Same da Vinci Style as "Mona Lisa"
But perhaps most exciting of all for the team investigating was that the portrait had clear stylistic similarities to that most famous of da Vinci portraits - the "Mona Lisa."
If they are correct, it will be the first major work by da Vinci to be identified in 100 years.
Silverman, who began the investigation , is still somewhat in shock. If it's provenance is proved it could be worth as much as $150 million.
The owner has apparently promised to buy himself "lunch and dinner and caviar for the rest of my life if it ever does get sold!"
The Associated Press contributed to this report.