The newspaper reported that Gatlin's tainted sample, taken April 22 at the Kansas Relays, tested positive for the steroid testosterone without traditional testing, instead going immediately to carbon isotope analysis (CIR).

The CIR test, requiring much more labor and costing up to 500 dollars a test, usually comes after a more typical test examines the ratio of testosterone to epitestosterone, also a naturally produced hormone.

Should that ratio exceed 4-1, testosterone-detecting CIR is then usually used. Either ratio or CIR testing can be declared as a positive doping result.

The Tribune reported that the lab testing Gatlin's urine sample was asked to first apply a CIR test, testers unaware the sample belonged to the 2004 100m Olympic champion who shares the world record of 9.77sec with Jamaican Asafa Powell.

Gatlin's A and B samples showed evidence of testosterone metabolites, the newspaper reported.

Gatlin, who faces a lifetime ban from the sport because of a prior doping violation, said he has never knowingly used testosterone.

An appeal where gatlin can present evidence is possible to the US Anti-Doping Agency and then to the Court of Arbitration for Sport.