Marble Run - G.S. Miller

Picture the art thief, the master forger. What do they look like? How do they act? You might imagine a debonair, Thomas Crown-esque character. Probably a multi-millionaire playboy who loves the thrill, the adrenaline, of the heist. Wavy salt-and-pepper hair, rugged good looks, sardonic smile, perhaps? A dashing rogue with a twinkle in his eye? Probably already seducing the lead investigator. 
Imagine all you want. What you've got is a twenty-something pasty-faced Canadian, tangled up in second-hand worker's clothes smelling of urine, sweat, and stale coffee. He can make a passable forgery, as long as no one looks at it too closely. He's managed to show some other people how to do so, too, which says something about his teaching ability. And he's been moderately successful at putting things into a museum, but that really just goes to show how unclear on the whole concept he's been.