The luxury cars lined up on Catron Road in a suburban subdivision north of Baltimore. A baby blue Rolls-Royce, a white Maserati, a black Bentley and two Ferraris. More than a dozen jammed the street and driveway in front of Rodney R. Hailey’s five-bedroom colonial.

Hailey told people that his company, Clean Green Fuel, was in the business of making renewable fuel, but some neighbors grew suspicious. One eventually complained to law enforcement officials.

That tip led authorities to uncover what federal prosecutors in Maryland say was a multimillion-dollar scam.

Hailey, they allege, never produced so much as a drop of clean biodiesel. They say he sold phony renewable-fuel credits to major oil companies, brokers and producers, then simply pocketed the cash, spending lavishly on cars and jewelry.