An underling to a famed Irish artist was busted this week for stealing a painting from his former boss, and trying to sell it at a posh Madison Avenue auction house, police said Saturday.

Arturo Rucci, 50, ripped off Sean Scully’s painting –valued at $400-600,000– and tried selling it last month, cops said.

Rucci brought the piece to Bonhams Auction House and identified himself as its legal owner.

But when rightfully-suspicious employers there called Scully, 72, to inquire further about the piece, the artist realized his painting was missing and called the police, cops said.

Rucci was arrested on Thursday afternoon and charged with criminal possession of stolen property.

Scully, who lives in New York, was most recently awarded Harper’s Bazaar Art International Artist of the Year in Hong Kong, China, according to his website. He did not immediately respond to request for comment. His abstract work has been shown at museums across the world, including the Guggenheim, the Art Institute of Chicago, The Metropolitan Museum of Art and the Tate Modern.