A federal appeals court on Wednesday ordered new sentences for two former National Century executives convicted in a $1.9 billion corporate fraud case once likened to the Enron scandal, saying the government had proved some but not all of its case.

A three-judge panel of the 6th U.S. Circuit Court of Appeals in Cincinnati overturned Donald Ayers' conviction of conspiracy to commit money laundering, and Roger Faulkenberry's conviction of money laundering and conspiracy to commit money laundering, saying the government didn't provide enough proof.

Remaining in place are Ayers' convictions of conspiracy to defraud the U.S. and securities fraud, and Faulkenberry's convictions of conspiracy to defraud the U.S., securities fraud and wire fraud.

Ayers, 74, is serving 15 years in Coleman federal prison in Florida after his 2008 conviction with Faulkenberry and four other top executives from National Century Financial Enterprises, a Columbus health care financing company. Federal prosecutors compared the case to Enron.

Faulkenberry, 49, is serving 10 years in Gilmer federal prison in West Virginia after his 2008 conviction.

The court said the government didn't prove that advances Faulkenberry and Ayers made to medical companies were designed to conceal the money's source.