Doctors Cast Doubt on Russian Skater’s Drug Test Contamination Claims

The latest revelations about Russian figure skater Kamila Valieva’s doping case raise more questions about the substances found in her sample—and the reasons why the 15-year-old might have failed the drug test. TIME asked leading experts to help make sense of the claims, which have upended the women’s figure skating competition at the Beijing Olympics and cast a larger pall over the sport.

At the hearing held on Sunday by the Court of Arbitration for Sport (CAS), anti-doping authorities revealed that Valieva tested positive for three heart treatment drugs, one of whi…