Has the mystery behind the 'Mona Lisa' been solved?

It took awhile, but he got her talking.

And she definitely had something to say. Some 500 years is a long time to keep a secret, especially for the most famous painting in the world.

Pascal Cotte believes he now knows what exactly is behind the Mona Lisa's teasing smile, a mystery that's fascinated art historians for ages.

Using a 240-million pixel camera of his own invention, this French physicist says he discovered two previous portraits Leonardo da Vinci painted underneath the enigmatic figure we call Mona Lisa.

So the world's most interesting woman just got more interesting. Cotte answered very few questions with his groundbreaking work but he created an entire encyclopedia of new ones about this painting and the man who held the brush that made her.

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Some of Cotte's newest discoveries will make their U.S. debut in "Da Vinci – The Genius," a traveling exhibit opening at Cincinnati Museum Center May 20. It features a few dozen of his most jaw-dropping findings, as well as 40 super-magnified, high-resolution sectional images of the "Mona Lisa."

"Da Vinci – The Genius" features more than 70 of da Vinci's inventions that the original Renaissance Man designed, but did not construct, in his lifetime. His unfinished thoughts are now considered the blueprints for the helicopter, airplane, automobile and submarine – just to name a few.

Some 6,000 pages of the Italian inventor, artist and scientist's drawings and writings inspired the 200-piece show.

Cotte's work on the famous painter's most famous painting garnered headlines around the world in 2015 after a BBC documentary highlighted his work. He's written a book, too, and is writing more about his findings.

"My goal now is to disseminate and explain all of the discoveries," he said on the phone from France,

The "Mona Lisa" is actually only one of 15 surviving paintings by da Vinci. Now the star of the Louvre Museum in Paris, the portrait is widely considered the most visited painting in the world with about six million people viewing her in her bulletproof casing each year.

Her reach, however, stretches way beyond the Louvre. Since its creation in the early 16th century, it's been parodied by the likes of everyone from Marcel Duchamp to "The Simpsons." The New Yorker notoriously recast Monica Lewinsky in the role for a cover during the Clinton impeachment trial.

Mona Lisa is a muse for musicians, too, from Nat King Cole to Elton John to Brad Paisley. But how does this painting that's not even 3-feet-long occupy such a massive cultural space for such a long time?

It's a question a lot of us ask. At least we ask Google: "Why is Mona Lisa so famous?" "So popular?" "So special?" are the top autocorrect questions in when you search through that online engine.

The mystery, of course, is part of her appeal. We aren't sure exactly who she was. A common answer is that Mona Lisa is actually Lisa Gherardini, the wife of a silk merchant. But why did da Vinci, who was in such high demand at the time, choose to paint her? Is that why she is smiling?

Maybe it's because we've always known there was something there. Something hidden behind that smile.

But more smiles behind that smile? Even Cotte didn't see that coming.

After developing his multispectral camera in 1998, Cotte earned a reputation in the art world as a bit of a Leonardo-level genius in his area of expertise.

In 2004, museum officials invited him to take photographs of the "Mona Lisa" to determine what the portrait would have originally looked like in the early 1500s before time muted and diluted the colors.

He determined the brighter colors of the original then. But Cotte had a secret of his own.

With the help of a sorting software, he next worked quietly for about 10 years documenting each layer of ancient pigment on the canvas. He wasn't sure what he was looking for in all those photographs but knew he had to keep looking.

Turns out, it was a bit obvious: "X" marked the spot.

In 2012, he discovered two crosses Leonardo da Vinci used to mark the gaze of the portrait sitter. But these crosses didn't align with Mona Lisa's provocative gaze.

"The glance is the key inside the portrait," he said. "Once you see the crosses, it gives you the position. And this is not the same."

Those crosses were his big breakthrough, Cotte said. His biggest surprise.

Art historians often cite another of his discoveries as the most shocking: One of the underpaintings includes an elaborate headdress usually reserved for celestial beings.

After spotting evidence of the headdress in his photographs, Cotte realized a shadow, so to speak, of one of the hairpins is actually visible to the naked eye. So is the decoration of a previous dress, he said.

So maybe Mona Lisa was whispering to us this whole time.

Want to go? 

For more info and to purchase tickets, visit www.cincymuseum.org/exhibits/da-vinci-the-genius.