She was history's most notorious femme fatale, with three husbands, numerous lovers, and a rumoured penchant for poisoning men of whom she grew tired. Yet not a single portrait survives of Lucrezia Borgia, the infamous Italian Renaissance noblewoman – or so it was believed until now.

After four years of detective work, the National Gallery of Victoria (NGV) announced yesterday that it had identified Borgia as the subject of a mystery painting held in its collection for more than four decades. The oval portrait is believed to be the work of Dosso Dossi (1486-1542), a contemporary of Titian, Raphael and Michelangelo, and to have been painted between 1515 and 1520.