(ANSA) - Florence, September 12 - The latest remains uncovered at a former convent in central Florence don't belong to the Mona Lisa - but she might be just underneath, a researcher says. The fourth skeleton found below the former Ursuline convent appears to belong to another noblewoman who may have sat as a model for Leonardo da Vinci when he was painting his famous work. And that suggests the real Mona Lisa might be buried right below, says Silvano Vinceti, who heads the investigating team looking for the remains of the Mona Lisa. "The ledgers kept by the nuns of this convent tell us that, presumably, the remains exhumed today are those of Maria Del Riccio, a wealthy woman who (died) in 1609," Vinceti told a news conference Wednesday. The method of burial used by nuns during this period - stacking graves one above the other - suggests that the Mona Lisa herself "could be right here" underneath the gave that contained Del Riccio, he said. For months, Vinceti has led a team working near the altar in the basement of the former convent of St. Ursula, where it's believed Mona Lisa, a Florentine noblewoman, was buried in 1542. La Gioconda - as the Italians call the Mona Lisa because of the surname of her husband, del Giocondo - is believed to have joined the Ursuline nuns in old age. It has frequently been suggested that del Giocondo commissioned Leonardo to paint his Mona Lisa (mona is the standard Italian contraction for madonna, or "my lady,") to mark his wife's pregnancy or the recent birth of their second child in December 1502. More digging in the site is required, said Vinceti. Meanwhile, the bones uncovered this week will be delivered to a team of specialists from the University of Bologna-Ravenna, Pisa, L'Aquila, and Puglia for analysis. Research should be wrapped up by next February, concluded Vinceti.