Leonardo da Vinci’s "Mona Lisa" is one of the world’s most intriguing paintings, but the latest finding added to the mystery of the 500-year-old masterpiece. There are several hidden portraits under the painting, French scientist Pascal Cotte claimed Tuesday, according to CNN and the BBC. One of them might be of Lisa del Giocondo, the woman who was possibly the model for the painting.

After 10 years of research, Cotte said, he was able to reconstruct a portrait of del Giocondo. “She is totally different to Mona Lisa today,” he told the BBC Tuesday. “This is not the same woman." Click here to see the reconstruction.

Cotte used a method he created, called Layer Amplification Method (LAM), to examine the "Mona Lisa." "We can now analyze exactly what is happening inside the layers of the paint and we can peel, like an onion, all the layers of the painting. We can reconstruct all the chronology of the creation of the painting,” he said.

So who is Lisa del Giocondo? Little is known about her, other than she was married to Florentine cloth merchant Francesco del Giocondo. She belonged to the prominent Gherardini family in Florence. Though it hasn’t been confirmed she was Leonardo’s subject, she was reportedly a neighbor of the artist.

In 2014, researchers started DNA testing on del Giocondo’s bones. They would compare the DNA to relatives in the Gherardini family to determine if she was the model. "If we don't find her, art historians can continue to speculate about who the model really was," art sleuth and historian Silvano Vinceti told the Wall Street Journal. 

The Louvre Museum in Paris, where the famous painting lives, did not issue a comment about the finding because it "was not part of the scientific team.”

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