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.
Lillian Schwartz
Schwartz used the works of Leonardo da Vinci extensively in experiments with computers. One notable work she created is "Mona/Leo", for which she compared the image of a Leonardo da Vinci self-portrait with the "Mona Lisa", matching the two faces feature by feature to show their underlying structural similarity. Specifically, she replaced the right side of the "Mona Lisa" with the flipped left side of a red chalk self-portrait of Leonardo. Superimposed lines drawn on the image showing the close alignments of the bottom of the eye, eyebrow, nose and chin prompted her to argue that the Mona Lisa is in part a cryptic self-portrait of the artist. In further experiments along these lines, she removed the gray tones in Leonardo da Vinci's self-portrait and superimposed the "Mona Lisa" eye over it. Not everyone is convinced by her argument for the identity of Leonardo da Vinci and the "Mona Lisa"; one common counter-argument is that the similarities are due to both portraits having been created by the same person and therefore bearing the hallmarks of a characteristic style. Additionally, though the drawing on which Schwartz based the comparison is held to be a self-portrait, there is no firm historical evidence to support this theory.