The Court of Arbitration for Sport (CAS) has named Russian curler Alexander Krushelnitzky as the athlete under investigation following a failed drugs test.
The buildup to the Winter Olympics in Pyeongchang was dominated by Russia's ban from the event due to state-sponsored doping in Sochi four years ago, with only athletes who had passed drugs tests and been confirmed clean allowed to compete under the banner of Olympic Athletes from Russia.
However, Krushelnitsky - who won bronze alongside his wife in the mixed doubles on Tuesday - is suspected of testing positive for meldonium, which is the same substance which led to Maria Sharapova's recent ban from tennis.
The 25-year-old is understood to have since left the Olympic Village and is now waiting in the Korean capital of Seoul for a B sample.
Meldonium, which was banned in 2016, increases blood flow and improves exercise capacity, although the president of the Russian curling federation claimed that all of the athletes returned negative tests as recently as January 22.