Germany's five-time Olympic medalist Evi Sachenbacher-Stehle has become the first athlete to be disqualified from participating in the Sochi Games for failing a doping test.
Sachenbacher-Stehle reportedly tested positive for the banned stimulant methylhexamine in two samples after finishing fourth in the 12.5-kilometer mass start on Monday, the German Olympic Committee said Friday.
The organization said that it had "as a result excluded Sachenbacher-Stehle from the Olympic team … and arranged and implemented her immediate return home."
Sachenbacher-Stehle said that she had not intentionally taken any banned substance.
"I am living through my worst nightmare right now. I cannot explain to myself where the positive sample generated from," she said in a statement issued by the German Olympic Committee.
"I had checked every dietary supplement in a laboratory before, to always be on the safe side. I can assure all involved parties, that I, at no time, took any forbidden substances. I will do everything in my power to clear up this case."
Athletes in sports as diverse as boxing and motorbike racing have been banned from competing because of methylhexamine, which can be found in some commercial dietary supplements.
There have been reports that two other athletes, a Ukrainian skier and an Italian bobsledder, may also have tested positive at the Sochi Olympics but neither report has been confirmed.
Russian biathlete Irina Starykh was removed from the national team prior to the Games after failing a drug test.
The Sochi Olympics will see more doping tests than any previous Winter Games, with a total of 2,453 tests to be completed.
Sachenbacher-Stehle, 33, won cross-country skiing gold medals in 2002 and 2010 and has three silver medals to her name. She switched to biathlon for the Sochi Winter Olympics.