
French poet Guillaume Apollinaire, who had once called for the Louvre to be "burnt down," 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.
At the time, the painting was believed to be lost forever, and it would be two years before the real thief was discovered. Louvre employee Vincenzo Peruggia stole it by entering the building during regular hours, hiding in a broom closet and walking out with it hidden under his coat after the museum had closed. Peruggia was an Italian patriot who believed Leonardo's painting should be returned to Italy for display in an Italian museum. Peruggia may have also been motivated by a friend who sold copies of the painting, which would skyrocket in value after the theft of the original. After having kept the painting in his apartment for two years, Peruggia grew impatient and was finally caught when he attempted to sell it to the directors of the Uffizi Gallery in Florence; it was exhibited all over Italy and returned to the Louvre in 1913. Peruggia was hailed for his patriotism in Italy and only served a few months in jail for the crime.
During World War II, the painting was again removed from the Louvre and taken safely, first to Château d'Amboise, then to the Loc-Dieu Abbey and finally to the Ingres Museum in Montauban. In 1956, the lower part of the painting was severely damaged when a vandal doused the painting with acid. On December 30 of that same year a young Bolivian damaged the painting by throwing a rock at it. This resulted in the loss of a speck of pigment near the left elbow, which was later painted over.

