The team is certain that Florentine Lisa Gherardini was the mysterious woman who sat for Leonardo da Vinci's portrait, but after years of research on skeletons unearthed in the Tuscan city, they have just one bit of femur that might match - and even that is too damaged for DNA testing.
Born in 1479, Gherardini was the wife of silk merchant Francesco del Giocondo. He is believed to have commissioned da Vinci to paint a portrait of her in 1503 - the one now hanging in the Louvre museum in Paris.
Gherardini lived out her final years a widower in a convent in Florence, where she died and was likely buried in 1542.
The researchers began exhuming skeletons in 2011 in the hope of finding her remains, unearthing a dozen in the process. While the first eight were well conserved, carbon dating tests showed they were too old to be the Mona Lisa.
The other four were found in a common tomb used until 1545, and carbon dating proved that one of those buried there - of which only fragments of the femur, shinbone and ankle remain - lived in the same period as Gherardini.
Historian Silvano Vinceti who lead the research said it was "a coming together of elements, from anthropological exams to historic documents, which allow us to conclude that the remains probably belong to Lisa Gherardini."
However, the hypothesis could not be put to the test through DNA analysis because the vault where the bodies were laid to rest was so humid that the skeletons deteriorated over the centuries, rendering such an exam impossible.
The lack of a skull also meant the team had to give up on their plan to try and reconstruct the face to compare it with the one da Vinci painted.
While the absence of concrete evidence may disappoint those hoping to have finally confirmed the owner of history's most enigmatic smile, it may cheer other art sleuths who believe da Vinci might have used a male model for the Mona Lisa - or that the sly grin is because the painting is a self-portrait.