Fraudster to the stars Kenneth Starr’s swanky Upper East Side condo sold yesterday for $5.6 million — about $2 million less than he paid using money stolen from actress Uma Thurman and heiress Rachel “Bunny” Mellon.

The winning bidder at the Treasury Department auction declined to give his name, but said he was a developer who bought the triplex on East 74th Street as an investment.

PHOTOS: KENNETH STARR SCANDAL

Starr — a money manager whose A-list clients also included Al Pacino and Lauren Bacall — was caught cowering in a closet after his $33 million Ponzi scheme collapsed in 2010.

He’s serving seven-plus years in the slammer and facing a divorce from his ex-stripper wife, Diane Passage.