Drug testers tried to track down shamed Greek sprint duo Costas Kenteris and Katerina Thanou for two days before the Games, athletics chiefs have confirmed.
International Association of Athletics Federation president Lamine Diack also revealed the pair had missed a third mandatory test earlier this year.
The missed tests in Athens on 12 August and Chicago on 10 August were preceeded by a test in Tel Aviv on 27-28 July.
Diack also confirmed they misinformed the IAAF of their whereabouts in 2003, saying they were in Crete, not Quatar.
Diack confirmed testers had first tried to locate the pair in Chicago on August 11-12, saying: "They weren't in Chicago, that's why the International Olympic Committee tried to test them in the (Olympic) village."
Thanou had been scheduled to remain in Chicago until 18 August while Kenteris was expected to remain until the 23rd August.
After failing to locate the pair the testers, working on behalf of the IOC which conducts all doping tests between 31 July-31 August, tried again unsuccessfully on 12 August to conduct a test in the Olympic village.
Diack added that both athletes had been tested twice in the past three months - once in May and once in June.
Kenteris had also undergone three tests last year and Thanou two.