The hidden portrait features a sitting subject who looks almost identical to the "Mona Lisa," minus small but significant differences.
The sitter in the image appears to be looking to the side rather than directly at the viewer, and the sitter does not seem to have the enigmatic smile that's intrigued "Mona Lisa" viewers for over 500 years.
Cotte told the BBC that he believes his findings challenge the widely accepted theory that the "Mona Lisa" is a painting of real-life 16th century Italian woman Lisa Gheradini, who was the wife of a Florentine silk merchant.
"The results shatter many myths and alter our vision of Leonardo's masterpiece forever," he said. "When I finished the reconstruction of Lisa Gherardini, I was in front of the portrait, and she is totally different to Mona Lisa today. This is not the same woman."
In an upcoming documentary for the BBC, art historian, Andrew Graham-Dixon, said he studied historical documents linked to the "Mona Lisa" alongside Cotte's findings and came to the same conclusion as Cotte.
"I think the new discoveries are like a huge stone thrown into the still waters of art history," Graham-Dixon said. "They disturb everything that we thought we knew about the Mona Lisa ... [T]here may be some reluctance on the part of the authorities at the Louvre to think about changing the title of the painting because that’s what we’re talking about. It’s 'Goodbye, Mona Lisa.' She is somebody else."
The Louvre Museum declined to comment on the findings, saying it was not a part of the scientific team that studied the painting.
Other art historians remain skeptical about the claims that Cotte's findings could prove the "Mona Lisa" was someone else other than Lisa Gheradini.
Oxford University Professor Martin Kemp, one of the world's leading experts on Leonardo da Vinci told the BBC that he believes Cotte and his team is "ingenious" but "the idea that there is that picture as if it were hiding underneath the surface is almost untenable."
He added, "I think there's no doubt it is Lisa."