Four Russian gold medalists allegedly used performance enhancing drugs while they were competing at the Sochi Winter Olympics.

According to CBS News, Vitaly Stepanov reveals this on 60 Minutes with Armen Keteyian. The excerpt is set to air on CBS Evening News this Sunday, May 7 around 6:30PM ET.

Vitaly came across the list after he chatted with Grigory Rodchenkov over Skype and recorded their conversation. Rodchenkov who headed Russia’s drug-testing labs, claimed he had a list of the athletes who tested positive for performance enhancing drugs wherein 4 on the list successfully bagged gold medals at the Sochi Winter Olympics.

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According to the CBS News, Vitaly further exposes Russian Intelligence officers saying “FSB tried to control every single step of the anti-doping process in Sochi.”

This wasn’t Stepanov’s first time to expose doping scandals. Late last year,the former head of the Russian Anti-Doping Agency together with his wife, Yulia, came out with damaging allegations that Russia had long been active in covering their athletes’ doping activities. The documentary which they helped make exposing Russia’s illegal doping ways was aired after they have secured safe passage out of Russia. The couple along with their son has since fled to the US, DailyMail has reported.

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Due to the Stepanovs’ exposure of Russia’s doping culture, Russia and its whole host of athletes has since been banned to every international competition.

With this recent whistleblowing report on the Sochi list, WADA is to meet in Montreal to revisit their whistblowing regulations, CBC Canada reports. Meanwhile, the World’s Anti-Doping Agency (WADA) has yet to launch the investigation. WADA spokesman Ben Nichols told ESPN that the organization “will watch the (’60 Minutes’) program with interest.”

Yulia Stepanov who was a former member of Russian track and field also admitted to using performance enhancing drugs before. With these revelations, she hopes it will help her petition to compete for the Rio Summer Olympics without a country.