By Mike Rowbottom

Travis Tygart, chief executive of the United States Anti-Doping Agency ©AFP/Getty ImagesTravis Tygart, the man who headed the investigation which led to Lance Armstrong's demise on drugs charges, believes sprinter Justin Gatlin, back in athletics after serving two doping bans, deserves a chance at "redemption".

The chief executive of the United States Anti-Doping Agency told BBC Sport that Gatlin, unbeaten over 100 and 200 metres this season, deserves another chance, despite the criticism which has been aroused by his nomination as one of 10 male athletes in line for the International Association of Athletics Federation's (IAAF) Athlete of the Year award.

"If somebody commits a violation, serves a ban and comes back to the sport, part of the rule is this idea of redemption," Tygart said.

In reference to research done recently by the University of Oslo indicating that muscles can retain advantages given by anabolic steroids decades after the point at which they were taken, Tygart said: "There is some recent science on the effect of steroids on mice, but there is no proof yet it translates to humans."

Tygart, who in 2012 declared the "conclusive and undeniable proof" that American cyclist Armstrong was a drug cheat who was at the heart of a team-run doping conspiracy, added: "We've looked at it and you have to be cautious about changing the goalposts in the middle of the game based on a few sound-bites in the press from one paper on mice.

"That's not fair.

"What's fair, and what athletes and the public rely on, is a set of rules that are enforced evenly."

Justin Gatlin deserves a chance to earn redemption despite having served two doping bans, according to Travis Tygart, chief executive of the US Anti-Doping Agency ©Getty ImagesJustin Gatlin deserves a chance to earn redemption despite having served two doping bans, according to Travis Tygart, chief executive of the US Anti-Doping Agency ©Getty Images

For an athlete who commits a doping offence, Tygart acknowledges that "there is always a cloud that follows that person, but that's not a question for the rules, that's people's opinions".

Earlier this week, Sebastian Coe, the man likely to be the next President of the IAAF, said he had a "big problem" with Gatlin's nomination for this year's Athlete of the Year award and told reporters he believed dopers enjoyed the benefits of their cheating long after their bans were over.

But Tygart told the BBC the Oslo study was not the first to show a long-term effect from steroids in mice, and that nobody had been able to demonstrate that the same applied for humans.

A revised version of the World Anti-Doping Code is due to come into force from January 1 next year, restoring the ban for serious offences to four years from two.

Tygart did not rule out further extensions.

"Fairness dictates that we stick to the rules, but if the science says we have to change the rules then, absolutely, let's do that."

Gatlin's fellow nominee for the World Athlete of the Year award, Germany's world and Olympic discus champion Robert Harting, has subsequently withdrawn his candidacy in protest.

But the IAAF maintain they have no option but to keep the American in the mix for the top honour.

"Gatlin, as an eligible athlete who has had a great season is, logically, also eligible for consideration for the Athlete of the Year contest in the absence of any bylaw to prevent that happening," an IAAF spokesman told Reuters.

Contact the writer of this story at [email protected]

Related stories
October 2014: Coe has "big problems" with Gatlin's IAAF award nomination
October 2014: Harting asks IAAF to remove him from World Athlete of the Year shortlist in protest at Gatlin nomination
October 2014: Drugs cheat Gatlin a controversial inclusion in IAAF World Athlete of the Year nominations