Isleworth Mona Lisa
According to Leonardo's early biographer Giorgio Vasari, Leonardo had started to paint "Mona Lisa" in 1503, but "left it unfinished". However, a fully finished painting of a "certain Florentine lady" surfaced again in 1517, shortly before Leonardo's death and in his private possession. The latter painting almost certainly is the one that now hangs in the Louvre. Based on this contradiction, supporters of the authenticity of the "Isleworth Mona Lisa" claim it is the unfinished "Mona Lisa", made at least partially by Leonardo, and the Louvre "Mona Lisa" a later version of it, made by Leonardo for his own use.
Mona Lisa
The fate of the painting around Leonardo's death and just after it has divided academic opinion. Some, such as Kemp, believe that upon Leonardo's death, the painting was inherited with other works by his pupil and assistant Salaì and was still in the latter's possession in 1525. Others believe that the painting was sold to Francis I by Salaì, together with "The Virgin and Child with St. Anne" and the "St. John the Baptist" in 1518. The Louvre Museum lists the painting as having entered the Royal collection in 1518.