And the smile of the Mona Lisa belongs to . . .

BERLIN -- A researcher has uncovered evidence that apparently confirms the identity of the woman behind the “Mona Lisa’s” iconic smile, Germany’s University of Heidelberg says.

She is Lisa del Giocondo, wife of Florentine businessman Francesco del Giocondo, according to notes written in the margins of a book by a friend of Leonardo da Vinci as the artist worked on the masterpiece, the school said in a statement this week.

The discovery by a University of Heidelberg library manuscript expert appears to confirm what has long been suspected. It is also an answer that has been in plain view for centuries: The “Mona Lisa” is known as “La Gioconda” in Italian.

Del Giocondo was first named as the likeness in the painting by Italian writer Giorgio Vasari in 1550, who also dated the work at between 1503 and 1506, the university said.

But because Vasari relied on anecdotal evidence, there were always doubts about the identification, and Leonardo is not known to have made any notes about the model’s identity himself. Compounding the mystery, vague references in 1517, 1525 and 1540 pointed to other identifications.

“One possibility discussed is the presentation of a fictitious likeness of a woman, Leonardo’s female ideal,” the school said.

But the find by Heidelberg library expert Armin Schlechter settles the matter, according to the university.

In a copy of the works of Roman philosopher Cicero, a Florentine official and friend of Leonardo’s wrote in the margins that the artist was working on a portrait of Lisa del Giocondo. The friend, Agostino Vespucci, dated his notes October 1503, also helping to pin down the exact time Leonardo was working on the painting.

“All doubts as to the identity of the ‘Mona Lisa’ are eliminated [by] one source,” the university said.

The discovery was actually made in 2005 but was not widely known until a German radio station aired it in a report last week.