Oakdale, La. ? Former WorldCom Inc. chief Bernard Ebbers drove through the gates of a federal prison Tuesday to begin a 25-year sentence for his role in the $11 billion accounting fraud that toppled the company he built from a tiny telecommunications firm to an industry giant.

Behind the wheel of a Mercedes he had driven from Mississippi, Ebbers pulled the bill of his cap down, shielding his face from reporters and photographers, as he drove into the prison.

At his home on Monday, he had refused to answer any questions and told an Associated Press reporter to leave.

Ebbers, a former high school basketball coach, was sentenced in July of last year after he was convicted of fraud and conspiracy in the massive fraud that drove Clinton, Miss.-based WorldCom into bankruptcy in 2002.

Investigators uncovered $11 billion in fraud at WorldCom, much of it because accountants were classifying regular expenses as long-term capital expenditures. The company re-emerged under the name MCI. Verizon later bought MCI.