The International Olympic Committee Saturday confirmed the first doping case of the Sochi Olympic Winter Games as German biathlete Evi Sachenbacher-Stehle tested positive for a stimulant.

Two-time Olympic champion Sachenbacher-Stehle, 33, tested positive on 17 February for methylhexaneamine, the IOC said in an announcement.

The IOC then disqualified her fourth place finish from both the women's 12.5km mass start and the mixed relay event. Her

The athletes has left the Olympic village.

German team's chef de mission Michael Vesper said an investigation is going on.

"The prosecutor's office was involved in the process yesterday and it is absolutely necessary that all the details of this case are carefully considered," he said at Saturday's German team press conference.

"We are all aware of the doping control rules and our athlete wanted to emphasise that it was not her intention to use this prohibited medicine. She was not aware she was taking a prohibited medical treatment and was not aware she was under threat of positive doping results." he said.

The IOC planned to carry out the most stringent Winter Olympic doping control program between Jan. 30 to Feb. 23. Within that period, the IOC systematically performs tests before and after events. After each event, the IOC systematically carries out tests on the top five finishers plus two at random. The IOC also performs out-of-competition unannounced tests. Over the course of the Sochi Games, the IOC is expected to carry out some 2,453 tests includling 1,944 urine and 509 blood.