SAN FRANCISCO — A federal grand jury is investigating whether Barry Bonds committed perjury when he testified in 2003 that he never used steroids, a person with knowledge of the probe told The Associated Press Thursday.

The person spoke on condition of anonymity because of the secrecy of the investigation.

The panel has been hearing evidence for more than a month about whether Bonds lied to a different grand jury that was investigating the BALCO scandal. The existence of the grand jury was first reported by CNN.

Bonds was granted immunity when he testified before the BALCO grand jury in December 2003, as long as he told the truth.