Rivkin was especially fond of photography, and he had quite an eye for beautiful and valuable pieces of art. His collection included works from luminaries like Alfred Stieglitz and Man Ray, and Christie's estimates a 19th century photo of the French naval fleet could fetch anywhere from $300,000 to $500,000. An image of a shell might go for $250,000 to $350,000.
In his plea agreement, Rivkin admitted that his company, Green Diesel, created the fake credits, and he faced over 10 years in prison and $51 million in restitution for the crime. In an announcement in June 2015, the EPA said that Rivkin admitted he abused renewable fuel credits, also known as renewable identification numbers (RINs), to make $29 million from oil companies. He pretended to have the RINs and sold them to the oil companies, who need to buy them (if they don't make enough biofuels) to prove to the EPA that they're in compliance with the renewable fuel standard.
A fascinating report at The Art Newspaper offers a deeper look at this fraudster's expensive taste, and the piece is well worth a read.