Irish Olympic hopeful Martin Fagan faces a disciplinary hearing in Dublin on Monday after a failed drugs test in Arizona.
The U.S.-based marathon runner was due to attempt to reach the Olympic qualifying time in Houston on Sunday.
Instead, the Mullingar native has flown home to defend himself after Athletics Ireland confirmed an "adverse analytical finding."
A statement from the governing body said: “Athletics Ireland can confirm that it has been advised of an alleged anti-doping rule violation by an Irish athlete following an adverse finding in a test taken in December last.
“The matter will now be the subject of a hearing before the Irish Sport Anti-Doping Disciplinary Panel which is to be convened in the very near future.
“Under the Irish Anti Doping Rules, Athletics Ireland cannot comment further until the Panel concludes its work and its final determination has been issued.”
Athletics Ireland won’t name Fagan until after the hearing has reached a conclusion and the B sample has been examined.
But the Irish Times has revealed that Fagan is the athlete in question and faces a two year ban if found guilty.
The paper reported: “All indications last night were that Fagan was caught using the blood-boosting drug erythropoietin - better known as EPO, and one of the most common, although largely out-dated, methods of performance enhancing.”
Traces of EPO were discovered in a sample taken during out of competition testing at Fagan’s US training base in December. He can now request a test of the B-sample.
The 28-year-old is a graduate of the scholarship system at Providence College, in Rhode Island, where he was coached by Ray Treacy, brother of Olympic medal winner John Treacy.
Fagan moved to Flagstaff in Arizona to train under American coach Greg McMillan but left that group in 2010.
He represented Ireland in the marathon at the Beijing Olympics but dropped out due to injury after the halfway mark.