Russian curler Aleksandr Krushelnitckii has professed his innocence, with staunch backing from the Olympic Athletes of Russia (OAR) team, after he failed a drugs test.
Krushelnitckii partnered wife Anastasia Bryzgalova to bronze in the mixed doubles at the Winter Olympics last week, beating Norway for a place on the podium.
However, the Court of Arbitration for Sport (CAS) confirmed on Monday that it had registered an anti-doping procedure involving Krushelnitckii.
The 25-year-old delivered a positive sample for meldonium, but insisted he was not to blame.
"I'm very sorry that the historical victory of Russian curling has now become the subject of a doping scandal, which is doing immense harm to our sport and to all Russian sports in general," Krushelnitckii told insidethegames.
"At the same time, I am ready to openly state that I have never, never during the time that I practice sport, used forbidden drugs and any other dishonest ways of competing.
"I am absolutely against doping and I have always tried to follow all anti-doping rules as closely as possible."
A remarkable OAR statement revealed they were pursuing a criminal investigation in order to ascertain how Krushelnitckii came to have the substance in his system.
"According to the unbiased results of laboratory analysis of Aleksandr Krushelnitckii's samples, detected concentration of the substance can be indicative of taking it once, which is not applied in medical practice and is absolutely useless and ineffective in the context of enhancing physical performance or sports results," read the statement.
"No evidence of the systematic usage of meldonium is available in this particular case.
"Therefore, the ROC [Russian Olympic Committee] has initiated a comprehensive investigation of the circumstances which also includes the criminal investigation under the RF [Russian Federation] criminal law to establish the facts of the case in detail."