The chief financial officer of Stanford Financial Group pleaded guilty in connection with a $7 billion international Ponzi scheme Thursday in federal court here.

James Davis, 60 years old, is cooperating with federal prosecutors, who are mounting a case against the chief executive of Stanford, R. Allen Stanford. Mr. Stanford was hospitalized Thursday morning because of a rapid heart beat.

Mr. Davis is facing up to 30 years in prison on charges of conspiracy to commit mail, wire and securities fraud as well as mail fraud and conspiracy to obstruct a Securities and Exchange Commission investigation. The government is seeking $1 billion from Mr. Davis.

"I did wrong. I'm sorry," Davis, the former Stanford chief financial officer said outside a Houston courthouse, after pleading guilty to fraud and conspiracy charges. "I apologize. I take responsibility for my actions."

Mr. Davis doesn't have the money, his attorney David Finn said.

Mr. Davis's assets have been frozen. He is living in Michigan and working a $10-an-hour manual labor job on a family farm in order to pay for his legal fees, Mr. Finn said.