Former WorldCom Inc. finance chief Scott Sullivan (search) took the stand Monday as the star government witness in the accounting fraud trial of ex-CEO Bernard Ebbers (search ).

Under questioning from prosecutor William Johnson, Sullivan began by answering routine queries about his background, education and family.

Click here to read the indictment against Bernard Ebbers

Sullivan, who pleaded guilty to fraud last year, is the linchpin of the government's case against Ebbers, who is accused of orchestrating the $11 billion fraud that drove WorldCom into bankruptcy in 2002. The company emerged from bankruptcy last spring and is known as MCI Inc. (search )

The government contends Sullivan was acting on orders from Ebbers when he directed WorldCom accountants to hide out-of-control expenses, and that the CEO was driven by keeping WorldCom in the good graces of Wall Street analysts.

Defense lawyers for Ebbers have said he was uneducated on accounting matters, preferring to be more of a visionary and cheerleader for the company and leaving the numbers to Sullivan.

Ebbers, 63, is accused of conspiracy, fraud and making false filings to the Securities and Exchange Commission (search ). The charges carry up to 85 years in prison.

Several other government witnesses have testified they took their concerns about shady accounting to Sullivan, and that Sullivan told them Ebbers was aware the accountants were unhappy with what they had been asked to do.