Johnson
Michael Johnson has rubbished claims from Justin Gatlin's coach Trevor Graham that the sprinter's failed drug test was a case of deliberate sabotage.
Graham said an aggrieved masseur rubbed testosterone cream into Gatlin's legs believing the sprinter had him sacked.
But BBC pundit Johnson said Graham could not be taken seriously as several of his clients were serving drugs bans.
The United States track legend wrote in the Daily Telegaph: "It's a new twist on an old excuse. Graham has no credibility."
Olympic and world 100m champion Gatlin, 24, has protested his innocence after announcing that he had tested positive at the Kansas Relays in April. He denies knowingly taking performance-enhancing substances.
But Johnson, a five-time Olympic gold medallist, wrote: "Graham has had several athletes who have tested positive or been banned from track and field.
"Yet Gatlin has continued his association with Graham knowing it would probably taint him.
"Even if Gatlin is innocent, he will be suspected forever and is about to see the danger of his continued association with Graham."
Graham, who also coached the disgraced former world record holder Tim Montgomery, was the whistle-blower who launched the Balco steroid investigation in California. He sent in the syringe to the authorities that sparked the scandal that rocked Ameri-can athletics.
And Johnson, a nine-time world champion, said: "I was always disappointed that more people did not ask the question: where did he get the syringe from?"
The world 200m and 400m record holder added: "With a confirmed A and B sample ... Gatlin should be banned for life unless he can quickly come up with proof that he did not knowingly take a banned substance.
"Circumstantial evidence produced by Gatlin, his coach and his lawyers that someone else is responsible should not be nearly enough.
"Graham should also be banned for life due to his involvement with an alarming number of athletes who have tested positive while training under him.
"Unfortunately, there is no rule in place to deal with coaches like him. And until there is, we might continue to see athletes cheating and damaging the sport."
