The Thieves
Only one thing was certain about the authors of the heist: they were a man and a woman. While the woman distracted the museum security guard, the man quietly creeped up the stairs and cut the painting from its frame.
Then, one of them had rolled up the painting and left the museum, keeping it under their coat. It was a smple plan; but it had been executed perfectly, and, in the end, it was successful.