Justin Gatlin insisted on running at the national championships in June even after USA Track & Field officials asked him to withdraw over his positive drug test, a person with knowledge of the meeting told The Associated Press on Friday.

Because only the “A” sample result was available from the April test, USATF had no authority to bar Gatlin from competing. Results of the backup “B” sample are required before a doping test is considered positive.

Gatlin professed his innocence to USA Track & Field officials when they suggested that he drop out of the meet, said the source, who asked not to be identified because of the sensitive nature of the information.

The 100 meters co-world record holder went on to win the national 100-meter title and was mobbed by fans afterward. Gatlin, who tied Jamaican Asafa Powell’s world-record mark of 9.77 seconds three weeks after his fateful drug test, has not raced since. He canceled several European appearances, citing a leg injury.

Gatlin’s agent Renaldo Nehemiah and his attorney Cameron Myler did not return telephone messages Friday.

Gatlin and USATF learned of the positive test just days before the U.S. championships began June 21 in Indianapolis. By then, it was too late remove Gatlin’s photograph from the meet’s posters and the many banners hung around the city. The 24-year-old sprinter showed up at the pre-meet news conference offering no hint of what was hanging over him.

“I’m going to strive for my goals, and I’m going to go out there and make sure I put the world record out of reach by the time I retire,” he told reporters.

Craig Masback, executive director of USA Track & Field, said he was shocked when he first learned Gatlin had tested positive after a relay race in Kansas in April.

“It’s a grave situation,” Masback said Friday in a telephone interview from Europe. “It’s a positive lab test for an athlete that has spoken clearly on the need to compete with integrity and without drugs.”

Gatlin, Masback acknowledged, had been the “standard bearer” for the anti-doping cause among U.S. athletes.

In early June, on the eve of the Prefontaine Classic in Eugene, Ore., Gatlin welcomed the role of leader of a young, talented group of U.S. track athletes.

“We have a lot of young athletes – Jeremy Wariner, Sanya Richards, Allyson Felix – who are running world-class times, proving to the world there’s no need for those cloudy allegations anymore,” he said at the time. “We’re trying to bring the sunshine back to track and field.”

Gatlin also acknowledged he always would draw suspicion because his coach is Trevor Graham – who has had numerous athletes suspended for doping – and because he was suspended as a young college sprinter for using a prescribed medicine to treat attention deficit disorder.

“It’s something I’ve grown to live with, something that keeps me fighting as an athlete, helping other sprinters and other youth come along and try to steer track and field in the right direction,” he said.

A reporter noted that if he ever did test positive, he would come across as one of sport’s greatest hypocrites.

“Yeah,” Gatlin said at the time. “My head’s on the chopping block.”

Gatlin has gone to his parents’ home in Pensacola, Fla., to await a hearing before a U.S. Anti-Doping Agency panel next week. Through his representatives, he has denied knowingly taking banned substances. Graham has blamed an Oregon massage therapist, who has denied any wrongdoing.

Under the World Anti-Doping Code, athletes are almost without exception held responsible for any substance found in their bodies, regardless of whether they had knowledge it was there. The standard for proving “exceptional circumstances” to lessen or drop any penalty is extremely high.

Some have suggested Gatlin’s best chance to save his career would be to accept the latest penalty but seek forgiveness for the positive test he had as a college freshman, when the medication was a legitimate treatment that was not banned by the NCAA.

Because of the two violations, the 24-year-old Gatlin faces a lifetime ban. He would be stripped of his share of the world record but would keep his Olympic gold 100-meter medal from 2004 and the world 100 and 200 titles he won in 2005.

Masback noted he always has said he expected more positive tests, just not from the athlete leading the charge against doping.

“We’re in the middle of this battle,” Masback said. “We’re not at the finish line. We’re maybe very early in the race.”