Federal prosecutors charged Tammy Thomas with lying when she denied using steroids allegedly provided to her by Patrick Arnold, an Illinois man at the center of the BALCO scandal.

Arnold testified Tuesday he had mailed steroids to Thomas, who was one of 30 athletes called to testify before a federal grand jury investigating BALCO, a Bay Area lab linked to such sports stars as Barry Bonds and disgraced U.S. sprinter Marion Jones.

The San Francisco Chronicle said the Thomas trial was being watched closely since the testimony could have an influence on Bonds' pending trial on similar charges of lying about use of performance-enhancing dugs.