Amid chaotic scenes, first Kenteris, then Thanou, then their controversial coach Christos Tzekos entered the Hilton Hotel and officially handed their Olympic accreditation over to the three-man IOC disciplinary panel.
While the two athletes independently strode out to protest their innocence to a massive media scrum, IOC judicial advisor Francois Carrard confirmed the case had been referred to the International Association of Athletics Federations (IAAF), who are expected to formally suspend the pair at a meeting next Thursday.
"The athletes have maintained they have done nothing wrong, which is their right and it is true they have never tested positive," said Carrard.
"But the disciplinary committee felt they had enough material and evidence to lead to a sanction for the Athens Games. In the end, the case didn't get that far because the athletes voluntarily agreed to surrender their accreditation."
Showing no sign of the injuries they spent five days being treated for following their mysterious motorcycle accident last Friday morning, the pair ended the IOC's concern with the case by yesterday's move.
At 31 and 29 respectively, it is conceivable neither will race again once the IAAF examines the case.
Under IAAF rules, three 'no-shows' for random drug tests means an automatic two-year ban.
The organisation already has one case - in Tel Aviv last month - awaiting investigation and the IOC have confirmed their testers unsuccessfully tried to meet Kenteris and Thanou twice during 'a general lack of information, misinformation and missed information about their whereabouts and availability from July 30 until they entered hospital on August 13'.
"We have clear rules about what constitutes a missed test and the IOC regulations compliment those of the IAAF, not contradict them," said IAAF anti-doping chief Arne Ljungqvist.
"We will probably not have a final ruling until well after the Games."
The IOC will reserve the right to oust anyone they think contributed to a saga that has overshadowed the first week of the Games.
IOC president Jacques Rogge set off on his trip to the ancient site of Olympia - the spiritual home of the Games - less than 30 minutes after Kenteris delivered a defiant speech and severed links with Tzekos.
"With a sense of responsibility and in the national interest, I am retiring from the Olympics," said Kenteris, who left hospital on Tuesday to tell the nation "after the crucifixion will come the resurrection".
He said yesterday: "I have passed 30 drug tests in the last four years. I declared the facts of my case which state that I am innocent."
Thanou, runner-up to Marion Jones four years ago, was unequivocal.
"The people who are accusing me are the ones who stood by me for photos after my victories; others don't know me.
"It's a very hard thing for an athlete to withdraw from the Olympic Games, especially when they are in your homeland."