SAN FRANCISCO — Olympic authorities now must decide whether Antonio Pettigrew will join the rogues gallery of athletes stripped of gold medals for doping.

Pettigrew admitted Thursday in a federal courtroom that he used banned performance enhancers from 1997 to 2001 after enjoying a long and successful career in which he passed all drug tests.

Federal prosecutors called Pettigrew to testify against his former coach, Trevor Graham, who is on trial for allegedly lying to investigators about his relationship with a prolific steroids dealer. Pettigrew, who is godfather to Graham's daughter, testified that he began doping at Graham's suggestion. He won a gold medal at the Sydney Games.

The U.S. Anti-Doping Agency, known as USADA and which polices Olympic hopefuls for drug use, declined to say if it would investigate Pettigrew.

"We will aggressively pursue any potential doping claims when we receive reliable information," said Travis Tygart, the agency's chief executive.

Olympic agencies such as USADA can rely on evidence other than positive drug tests to strip athletes of their awards and records. Marion Jones, for instance, was stripped of the five medals she won in Sydney after admitting in federal court that she was a doper.

Pettigrew's admission came during the last day of testimony for the government in Graham's trial. Graham has pleaded not guilty to three charges of making false statements.

Pettigrew testified that Graham encouraged him in 1997 to inject human growth hormone and the oxygen-boosting drug EPO, both banned in track. Soon after, Pettigrew said, he began buying the drugs from Angel "Memo" Heredia, an admitted steroids dealer from Laredo, Texas.

Once he began taking the banned substances, Pettigrew said he was able to run 400 meters in the 43-second range for the first time.

"I was running incredible times as I was preparing for track meets," Pettigrew said during 30 minutes of testimony. "I was able to recover faster."

Pettigrew initially lied to federal investigators and denied doping when they first talked to him in February 2005. But he finally confessed behind closed doors to cheating when confronted with documents in October 2006 strongly suggesting drug buys from Heredia.