Leonardo da Vinci used a male model, his lover, to paint the Mona Lisa, Italian researchers said Wednesday.
The Mona Lisa's real identity has remained shrouded in mystery, with a silk merchant's wife, Lisa Gheradini, being seen as the most likely model for the painting.
Now Silvano Vinceti, chairman of Italy's National Committee for Cultural Heritage, has said that the Florence-born Renaissance artist's male apprentice and likely his lover, Salai, was the main inspiration for the picture, Agence France-Presse reported.
Vinceti said da Vinci had left clues to the model's identity in tiny letters L and S which he and his team found painted into the eyes of the Mona Lisa.
"Close examination of a high-quality digital copy of the portrait had revealed an L for Leonardo and an S for Salai," he said, adding that he'd analyzed the copy using state-of-the-art high-magnification techniques.
Vinceti's team first claimed the existence of tiny letters and numbers painted into the eyes of the Mona Lisa last December.
In the right eye appeared to be the letters LV — which could stand for Leonardo Da Vinci — while in the left eye there were symbols.
Vinceti said: "It is very difficult to make them out clearly but they appear to be the letters CE or it could be the letter B — you have to remember the picture is almost 500 years old so it is not as sharp and clear as when first painted."
His latest claim was immediately disputed by experts at the Louvre in Paris, where the painting is on display. Museum officials said Vinceti had made his claims without having had access to the painting itself.
The museum told AFP that it had carried out "every possible laboratory test possible" on the picture in 2004 and then again in 2009, and found "no inscriptions, letters or numbers."
"The ageing of the painting on wood has caused a great number of cracks to appear in the paint, which have caused a number of shapes to appear that have often been subject to over-interpretation," a Louvre spokesman said, according to AFP.
Vinceti, whose team gained notoriety last year with their claims surrounding the death of Caravaggio, said he felt sorry for the embarrassment the museum must feel on having missed the clues all these years.
"I can understand their incredulity and amazement — after all this must be the most studied picture on earth," he told AFP, but added "they're really blind."
"They have to be serious and accept that they didn't see what was right in front of their eyes," he said.
Vinceti said Salai, real name Gian Giacomo Caprotti, an effeminate young artist who worked with da Vinci for 25 years, may have served as a model and muse for several of the artist's paintings. The pair had an "ambiguous" relationship and were probably lovers, he said.
Comparisons between the facial characteristics of figures from several of da Vinci's works — such as "St. John the Baptist" and the "Angel Incarnate" — reveal striking similarities with the Mona Lisa's nose and mouth, he told reporters.
Art historians have long theorized about the Mona Lisa, as well as da Vinci's other works of art.
Last month, Italian art historian Carla Glori, claimed that the painting identified the exact location of the landscape which provides the background of the painting.
She said a three-arched bridge appearing over the left shoulder of the woman was a reference to the village Bobbio, which is south of Piacenza, in northern Italy.