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.
Louis Lépine
The theft on August 22, 1911 of the Mona Lisa from the Musée du Louvre was more of an embarrassment to Lépine although initially he acted with his usual decisiveness ordering the museum to be closed for a week whilst forensic analysis was carried out.
French poet Guillaume Apollinaire came under suspicion; he was arrested and put in jail. Apollinaire tried to implicate his friend Pablo Picasso, who was also brought in for questioning, but both were later exonerated. The real thief was Louvre employee Vincenzo Peruggia an Italian wishing to return it to Italy. He was caught with the painting two years later when he attempted to sell it to the directors of the Uffizi Gallery in Florence.