One has to credit these athletes, who, recognizing that cheating by elite American stars has tarnished their sport into virtual irrelevance in their country, are trying to find a new path. But they face a daunting task if they hope to rehabilitate their sport’s image. Recent history has taught us that the simple fact that an athlete denies ever having tested positive for drugs is no proof that he or she doesn’t use them.

“I have been tested repeatedly and never tested positive for drugs” is the familiar refrain of some of America’s biggest stars—including Marion Jones and Barry Bonds—who find themselves the target of drug allegations. Jones can still make that claim today, despite the fact that she is now in prison for lying to federal investigators and has forfeited all five medals from her triumphant Sydney Olympics. Bonds can make that claim too, though he is on the baseball sidelines, still waiting for a team to give him a contract and looking ahead to a federal trial on multiple charges of lying to a federal grand jury about his use of steroids.

Antonio Pettigrew is another former U.S. Olympian who has never tested positive for drugs. A member of the American gold medal 4x400 relay team in Sydney, Pettigrew has been a mainstay of the U.S. track team. He was a member of winning relay teams at three successive world championships from 1997 to 2001 and ran a leg on the relay team that set the world record in 1998. Off the track he has been a leader and role model for athletes, serving as an officer on the USA Track and Field’s athletes’ advisory committee and as an athlete representative to the USOC. Pettigrew is currently an assistant coach at the University of North Carolina.

But last week Pettigrew was forced to shed the “I have never tested positive” defense and, testifying under oath in the trial of his former coach, Trevor Graham, tell the painful truth: that Pettigrew used illegal drugs for four years, from 1997 to 2001: human growth hormone to build up strength and EPO to increase endurance. While some of his gold medals will stand because they extend back beyond the eight-year statute of limitations, his 2000 Olympic gold and those of his relay teammates are in jeopardy.

Jerome Young, a teammate of Pettigrew’s in the Graham stable, was banned for life for two doping offenses and stripped of the Olympic medal, though a sports arbitration court allowed his teammates to keep theirs because there was no evidence that he was doping in Sydney and he did not run in the finals.

Graham himself is on trial in federal court in San Francisco on three counts of lying to federal investigators in a drug investigation and faces up to 15 years in prison. The case went to the jury Tuesday. Young also testified in the Graham trial, indicating that he used drugs first provided to him by Graham from 1999 to 2003—Sydney apparently no exception. That Sydney Olympic relay team, which included the last golden performance by the great Michael Johnson, now seems certain to lose its medals.

For Graham, once the coach of the brightest array of track stars, including Jones and Athens 100-meter Olympic champ Justin Gatlin, it has been a dizzying fall from grace. Remarkably, he set the events in motion not by his alleged cheating but because it was Graham who secretly sent a vial of an undetectable steroid to USADA.

It has never been exactly clear what his motives were or what he expected to happen. Perhaps, tired of hearing rumors and allegations about his program and his athletes, he hoped to drop a dime (or a vial) on a rival coach. He certainly couldn’t have imagined how wide the net would be cast. The vial led to a massive federal investigation, beginning with the raids on BALCO, a self-described hi-tech nutritional company, and ensnared dozens of athletes including Jones and Bonds. And ultimately it came full circle back to Graham.

I do salute the current athletes who at great inconvenience are going above and beyond what is required of them to try to prove that they are clean. And I applaud the news that Olympic drug testers will be going after cheats in Beijing like never before, with more random tests. And, hopefully, they will be armed with a reliable test for HGH that has been, for a couple of Olympics now, rumored to be on the way but then always turned out to be missing from the testing arsenal.

But cynicism tends to protect one against disappointment and has pretty much always proved to be the smarter response in these matters. I hope these Beijing-bound athletes are clean and that they return the sport to a righteous path. But nothing in recent history suggests that will turn out to be the case. The science of cheating has always outpaced the science of detection. And while the lessons from the fall of Jones and others is no doubt chastening, there will always be those who see the lesson in a slightly different light: that Jones would never have become America’s Olympic queen had she not cheated in the first place, and that her only mistake was getting caught.