Sport Ireland have revealed that Kerry forward Brendan O'Sullivan ingested the banned substance 'M-H-A' from a fat-burning supplement which O'Sullivan claims was contaminated.
He served a 21-week suspension after testing positive for M-H-A after the National Football League Final in April 2016.
O'Sullivan had been taking 'Falcon Labs Oxyburn Pro Superthermotech' and says the label didn't list M-H-A and it didn't appear in an internet search about the product.
In a statement issued jointly by the GAA and Sport Ireland confirms testing showed it was a contaminated product and O'Sullivan was not at fault.
"Mr. O'Sullivan explained that he took a supplement called Falcon Labs Oxyburn Pro Superthermotech. He asserted that it was a contaminated product as defined in the Irish Anti-Doing Rules because MHA was not disclosed on the label or in a reasonable internet search which he asserted he had carried out before taking the product.
"After analysis by Sport Ireland, carried out at the WADA-accredited laboratory in Cologne, of tablets left over from the original tub which Mr. O'Sullivan purchased and analysis of tablets from an unopened tub of the same product and consideration of sworn testimony from Mr. O'Sullivan regarding the internet search he had carried out, Sport Ireland accepted that it was a contaminated product case, that Mr. cO'Sullivan bore no significant fault or negligence and specified a sanction of 7 months which it considered appropriate.
"Mr. O'Sullivan declined to accept the specified sanction and on 5th January 2017 the matter was referred to the GAA Anti-Doping Hearings Committee.
"The hearing of the GAA Anti-Doping Hearings Committee took place on 14th February 2017 and a written decision was delivered on 27th February 2017. The GAA Anti-Doping Hearings Committee imposed a sanction of 26 weeks.
"On 16th March 2017 Mr O'Sullivan indicated he wished to appeal that decision to the Irish Sport Anti-Doping Disciplinary Panel. The hearing of the Irish Sport Anti-Doping Disciplinary Panel took place on 30th March 2017.
"On 7th April 2017, the Irish Sport Anti-Doping Disciplinary Panel advised the parties that it had determined that the sanction should be reduced from 26 week to 21 weeks. It indicated that a written reasoned decision would be provided as soon as reasonably possible. That reasoned decision was received earlier today.
"Mr. O'Sullivan was provisionally suspended from the 13th of May 2016 to the 28th of July 2016, a period of 11 weeks at which time his provisional suspension was lifted by the Chair of the Irish Sport Anti-Doping Disciplinary Panel under Article 7.8.3 because the violation was likely to have involved a contaminated product and the remaining 10 weeks of ineligibility was deemed by the Irish Sport Anti-Doping Disciplinary Panel to have commenced on the 26th February 2017, the date of his last participation in the Kerry panel."