The Olympic Games in Sochi were hit by a third doping case on Saturday after a Ukrainian skier failed a drugs test, as German prosecutors searched the home of a double Olympic gold medal-winning biathlete.
The Ukrainian Olympic Committee said on Saturday that cross country skier Marina Lisogor had tested positive, coming after German biathlete Evi Sachenbacher-Stehle and Italian bobsledder William Frullani also failed tests.
Sachenbacher-Stehle was expelled from the Winter Olympics on Friday after testing positive for a banned stimulant during the Games, sending shock waves through German sport.
The Ukrainian Olympic Committee said Lisogor, 30, told a disciplinary hearing that she had unwittingly consumed the banned substance in a medicine.
"The decision about the future fate of the athlete will be taken in line with IOC rules," the Ukraine Olympic Committee said.
It said it had been informed by the International Olympic Committee that the banned substance was trimetazidine, which was included on the banned list from January 1, 2014 and improves glucose utilisation.
Sachenbacher-Stehle, 33, said she consumed the banned stimulant methylhexanamin accidentally in a dietary supplement, adding she was living through the "worst nightmare you can imagine".
Germany's chef-de-mission at the Games, Michael Vesper, said Munich prosecutors had conducted searches in Ruhpolding, the Bavarian base of the German biathlon team, and at the athlete's home.
"It is necessary to investigate the environment in which this happened," he said. "We will cooperate with the prosecutors and it is right that they are acting."
But he added: "For us it is incomprehensible why such an experienced athlete should expose herself to such dangers" by taking such supplements.
He said while dietary supplements were not illegal, the German team had warned athletes against taking them as they can be contaminated or contain banned substances.
He said Sachenbacher-Stehle was "shattered" and that the "ground had been pulled from under her feet".
'Determined to catch cheats'
The athlete had explained that she obtained the products from a "mental trainer", Vesper added, adding this individual was not part of the German team.
Initial reports said the substance may have been consumed in something as mundane as an energy bar. But the mass circulation newspaper Bild said it may have come from a special "good mood" tea.
Sachenbacher-Stehle spent most of her long career as a cross country skier before switching to biathlon, which mixes cross country skiing and shooting.
It was as a cross country skier that she won gold in the 4x5 km relay in the Salt Lake City Games of 2002 and then gold in the team sprint in Vancouver 2010.
According to German media reports, the investigation opened by Bavarian prosecutors is into persons unknown and not against Sachenbacher-Stehle personally.
The Italian Olympic Committee said it had thrown Frullani out of the Games after he tested positive for the banned substance banned substance dymetylpentylamine.
Frullani -- a former international-level decathlete -- had "at best been extremely silly", said the president of the Italian Olympic Committee (CONI) Giovanni Malago.
The IOC, which oversees drug testing at the Olympic Games, is carrying out almost 2,500 drug tests at Sochi 2014 with an extra emphasis on out-of-competition tests.
"It is always disappointing when we catch people," said IOC spokesman Mark Adams. "But what it shows is a determination to catch cheats."