The Woman Behind the Smile: Who Was Really Mona Lisa?

Her name was Mona Lisa.

She was a beloved wife and mother of five who lived in Italy 500 years ago. For some, the best-known smile in the whole world belongs to her.

Following 25 years of searching Florence's city archives, high school teacher Giuseppe Pallanti located this unknown and mysterious woman's burial site, giving her a life story and a new identity.

He concluded that Giorgio Vasari, the architect of the Uffizi Gallery in Florence, Italy, might not have been wrong when he wrote that Lisa Del Giocondo, also known as Mona Lisa, was Leonardo da Vinci's "La Gioconda."

"I challenge anyone to explain to me the need for the most famous architect of his time, a man of success and considerable fortune, to invent a fabricated story knowing that he would have to face a whole town full of living relatives of Mona Lisa," Pallanti said.

Pallanti, who is not an expert or an academic, has developed a deep fascination for this figure. For a quarter of a century, he has spent all his free time digging up the pieces of a puzzle that eventually became a full portrait.

"I was stubborn, and I got to find pieces of evidence for baptism, birth, marriage, children, Mona Lisa's relationship with her husband, her husband's personality, and above all, social relationships that Giocondo's family had with some artists and more specifically with Leonardo's family," he said.

Tracing Love and Marriage and Death

A death certificate found by the amateur historian shows that Giocondo died in July 1542 in Florence and is buried in a convent in the heart of the city. The woman's death is now considered one of the most important pieces of evidence of her life.

Pallanti also traced the date of her wedding, at age 16, to Ser Francesco del Giocondo, a wealthy silk merchant who was 14 years her senior. His will says that she was his "beloved and ingenuous wife" -- an honest and devoted spouse.

Although Pallanti confined his research to the details of a single Renaissance woman's life, his studies gave weight to the very famous architect and artist biographer Vasari's original idea that Giocondo was in fact Mona Lisa, La Gioconda.

When asked whether he believed this theory, he said to ABC News, "Look, it was as though Renzo Piano [the famous modern Italian architect] said that a great artist had painted Marilyn Monroe or Sofia Loren."

Neighbors Perhaps but the Mystery Over the Smile Lingers

Concluding that, it would be simply impossible not to believe him. Why then does Pallanti believe Giocondo was Mona Lisa? His research revealed the Giocondo family resided in Via Ghibellina in Florence around the corner from where da Vinci lived with his family.

Ser Piero da Vinci, Leonardo's father, was a notary who drew up a number of deeds for Francesco Giocondo, Lisa's husband.

Apparently, Piero was a far more practical man than his son when it came to money matters, and he commissioned the portrait of Mona Lisa for his neighbors to give his son financial support.

But knowing who possesses that 500-year-old smile is still tricky because unlike many pictures of its time, this panel is not signed or dated and bears no clues as to the identity of the model.

Nevertheless, Pallanti's new finding doesn't seem to end a debate that has had some provocative theories.

Alessandro Vezzosi, a da Vinci historian and the director of a museum dedicated to the artist in his hometown of Vinci, told ABC News that although he absolutely respected Pallanti research, he didn't believe Giocondo was Mona Lisa.

"Leonardo himself said to Cardinal d'Aragona, when he went to visit his studio in Amboise, [France], that the portrait was for Giuliano dei Medici [a Florentine nobleman] and represented his lover," he said. "We have a record of that in a manuscript written by the cardinal secretary."

Vezzosi believes that Vasari wasn't referring to La Gioconda when he described Mona Lisa's painting. He points out that the famous architect praised the beautiful eyelashes of Mona Lisa, which are absent in Leonardo's work.

Other scholars think the painting is a portrait of Leonardo's mother. Others see it as a playful self-portrait of the artist, now thought by some to be homosexual, in a female form, or one of his favorite male lovers in disguise.

A group of medical researchers has maintained that the sitter was undergoing a mercury treatment against syphilis that turns teeth black, explaining why she keeps her mouth so firmly shut.

An American dentist's theory is that she had lost her front teeth and was trying to protect her beauty.

One thing is for sure: The debate over Mona Lisa's identity will continue.