In 1911 Vincenzo Peruggia perpetrated what has been described as the greatest art theft of the 20th century. The former Louvre worker hid inside the museum on Sunday, August 20, knowing that the museum would be closed the following day. Emerging from his hiding place on Monday morning, he wore one of the white artists’ smocks that museum employees customarily wore and was indistinguishable from the other workers. When the Salon Carre where the Mona Lisa hung was empty, he lifted it from the wall and took it to an enclosed stairwell. There he removed the protective case and frame and concealed the painting (which Leonardo painted on wood) under his smock. He left the Louvre with it, passing a guard station which had been left unattended by a guard who had gone to obtain a pail of water.

Vincenzo hid the painting in his apartment in Paris. Supposedly, when police arrived to search his apartment and question him, they accepted his alibi that he had been working at a different location on the day of the theft.

http://en.wikipedia.org/wiki/Vincenzo_Peruggia

http://query.nytimes.com/