KRASNAYA POLYANA, Russia >> At the midpoint of the Sochi Games, not yet marred by a single case of doping, the IOC’s top medical official said its efforts to catch drug cheats were so successful they had scared them all away.

A week later, after the disclosure of a fifth doping case on the final day of the games, IOC President Thomas Bach cited the positive tests as the sign of success.

Who’s right? To Bach, it doesn’t much matter.

“The number of the cases for me is not really relevant,” Bach said. “What is important is that we see the system works.”

During the course of the Sochi Olympics, Bach said Sunday, more than 2,631 athlete samples were analyzed for doping — nearly 200 more than planned. It wasn’t until the final few days of the games that any came back positive, although it’s possible more could be announced in the next few days as tests are completed on samples taken in the final week of the games.

None of the five athletes thrown out of the games for doping in Sochi won medals, and four of the five tested positive for minor stimulants that can be found in food supplements and often result in lesser sanctions.

“When you look at the substances taken, most of them stimulants, which have been detected, then look at the quantities, you see how far advanced the analysis is,” Bach said.

The fifth positive was for EPO, the classic doping substance of choice in endurance sports. It’s used to boost an athlete’s count of red blood cells, which carry oxygen to the muscles, increasing stamina and endurance.

Austrian cross-country skier Johannes Duerr admitted to using EPO after he tested positive in a sample taken in Austria, where he had returned for training after competing on Feb. 9 in the men’s skiathlon. He placed eighth.

“This is the worst thing I’ve done in my life,” Duerr told Austrian TV. “This is very, very tough. You can’t explain this in three sentences.”

Duerr was sent home hours before he was due to compete in Sunday’s 50-kilometer mass start cross-country ski race. In Sochi, Austrian Olympic Committee President Karl Stoss said “it’s a black day for us” and tried to distance his team from Duerr. The positive comes eight years after the nation’s cross-country and biathlon teams were involved in a blood-doping scandal that tarnished the 2006 Turin Olympics.

“The athlete himself confessed that he is the only one who did that and he takes all the responsibility on himself,” Stoss said.

Austria’s sports director for cross-country, Markus Gandler, said the “team is broken” and called Duerr’s actions a matter of “heavy doping.”

“This should be punished,” Gandler said. “I called him a ‘dream guy’ two days ago. What should I call him now?”

The 26-year-old Duerr has been the leading athlete in a new generation of cross-country skiers attempting to rebuild the sport’s image in Austria. He debuted on the World Cup circuit in 2011 and finished third in this season’s overall Tour de Ski standings.

“It’s a great pity that after all successful participations of the Austrian team we have had this case of doping,” Stoss said. “We will do everything that is needed of us to prevent this in future. But, of course, we can’t say there will not be one.”

The IOC stores Olympic doping samples for retesting years later when new methods become available. The storage period grows from eight to 10 years under revisions to the World Anti-Doping Code that take effect in 2015.

The issue of doping in Turin will return not long after the Sochi Games end, when the IOC is expected to announce the results of fresh analysis of hundreds of eight-year-old samples.

Acting on a tip, Italian police raided the Austrian cross-country and biathlon team’s lodgings in Turin and seized blood doping equipment and other substances. No Austrians tested positive at those games, but the IOC later banned several for life.

The Estonian Olympic Committee said this month that retired cross-country ski champion Kristina Smigun-Vahi, who won two gold medals in Turin, was under investigation by the IOC for a positive test.

The four other athletes thrown out of the Sochi Games for a positive doping tests were: Latvia hockey player Vitalijs Pavlovs, Ukraine cross-country skier Marina Lisogor, Italian bobsledder William Frullani, and biathlete Evi Sachenbacher-Stehle of Germany. As a cross-country skier, Sachenbacher-Stehle won gold medals in team events at the 2010 Vancouver Olympics and 2002 Salt Lake City Games.

World Anti-Doping Agency director general David Howman said in an email he could not comment on the cases until the body’s monitoring team in Sochi completed its report.

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AP Sports Writers Stephen Wilson in Sochi and Eric Willemsen in Krasnaya Polyana contributed to this report