The government rested its case Wednesday against Bernard Ebbers (search), the former CEO accused of orchestrating the $11 billion accounting fraud that sank WorldCom Inc (search).

Federal prosecutors rested after calling 14 witnesses over 16 days of testimony. The defense called its first witness, Cynthia Cooper, the internal auditor credited with blowing the whistle on the fraud at WorldCom.

Click here to read the indictment against Bernard Ebbers

After the government finished its case, U.S. District Judge Barbara Jones denied a defense motion to acquit Ebbers on all counts. The defense claimed prosecutors had not proved WorldCom's accounting violated generally accepted accounting principles, but Jones ruled they did not need to meet such a requirement.

The key prosecution witness was Scott Sullivan (search), WorldCom's former chief financial officer, who testified that Ebbers ordered him to carry out the enormous fraud.

Other government witnesses included three former WorldCom accounting executives who have pleaded guilty to participating in the fraud. One of them, David Myers, said Ebbers once apologized to him in a hallway for what the accountants had been forced to do.

A former Bank of America account manager also testified about the $400 million in personal loans Ebbers took out, backed by WorldCom stock and later shored up by guarantees from WorldCom's board of directors.

The government contends Ebbers, worried about margin calls on the loans, was obsessed with keeping WorldCom's share price high and producing revenue and earnings figures that pleased Wall Street.

But the star witness was Sullivan, who testified he repeatedly warned Ebbers from 2000 to 2002 that falsifying the books was the only way the company could meet stock analysts' expectations.

Time after time, he said, Ebbers came back with the expression, "We have to hit our numbers." Sullivan testified he interpreted that remark as a command to commit accounting fraud.

On cross-examination, Sullivan admitted he had lied to WorldCom's board, Wall Street, even his own friends. He has also admitted to using marijuana and cocaine while working for WorldCom, though never during working hours.

The defense has also sought to show that Sullivan was willing to tell prosecutors what they wanted to hear in hopes of eventually winning a lighter sentence.

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

WorldCom was forced into bankruptcy in the summer of 2002 when the fraud came to light. It has since re-emerged under the name MCI (MCIP), which is being bought by Verizon Communications (VZ) for $6.7 billion in cash and stock.