A French scientist claims ten years of analysis reveals Leonardo da Vinci's Mona Lisa has got another portrait underneath its layers of paint, and it is the face of another person. Pascal Cotte says his use of Layer Amplification Method (LAM) shows another woman's portrait was painted before the famous and enigmatic smiling face known the world-over.

BBC reports the LAM technique was pioneered by Cotte who says, "We can now analyse 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."

Cotte adamantly believes the sitter seen on the Louvre's walls is not Lisa Gherardini, the wife of a Florentine merchant, who has been widely-considered the subject. 

Experts are not all convinced of the second sitter theory and the Louvre has not commented. The Guardian's Jonathan Jones outright opposes Cotte's conclusion, noting Vasari's (and others') precise documentation of the painted portrait seen today and the sitter's name. He points out that the artist worked on the painting for several years from 1503 on and the finding of pentimento (evidence of re-painting) is not so surprising for any artwork, especially the masterwork of a genius. 

Writes Jones of Leonardo's process for Mona Lisa, "He worked on this portrait until the face of a real person was transformed into a myth."