Hajo Seppelt’s explosive documentary “The Doping Secret: How Russia Creates Champions” premiered on German television late last year presenting a damning look at entrenched and systematic state-sponsored doping by Russian athletes facilitated and encouraged by deep-rooted corruption and high-level cover-ups.

The report triggered a public outcry and an 11-month investigation by the World Anti-Doping Agency (WADA) that put the country’s once mighty All-Russia Athletic Federation (ARAF) through the ringer. The ordeal culminated on Nov. 13 when the International Association of Athletics Federations (IAAF) suspended Russian athletes from international competition, a move that could keep them from competing at the Olympics in Rio de Janeiro next year.

Speaking to Variety, Seppelt, an investigative journalist with pubcaster ARD, says he was caught off-guard by the impact his film has had. “I was sure that it would at least lead to some sort of political reaction, but the extent of the whole reaction was unexpected and a new experience for me.”

Indeed, former WADA president Richard Pound, who led the agency’s investigation of Russian athletics and the sport’s governing body, has compared Seppelt’s work to that of Bob Woodward and Carl Bernstein.

“This is the biggest compliment we can ever get for our whole team at the ARD doping research department. It was surprising that people compared  us with them but obviously it shows that what we have done was worthwhile.”

The scandal, stemming from one of the biggest sports stories of the decade, has not surprisingly made “The Doping Secret: How Russia Creates Champions” and Seppelt’s follow-up documentary, the award-winning “Doping – Top Secret: The Shadowy World of Athletics,” top international sellers.

Anne Hufnagel, general manager of Cologne-based Autentic Distribution, which is handling world sales for the documentaries, says the titles have been snapped up by major broadcasters around the globe, including  TV Globo in Brazil, Al Jazeera and Canal Plus in France as well as leading broadcasters throughout Europe.

Seppelt says the film, which originally aired Dec. 3 on ARD, was initially under the radar “because this was the time of the Ukrainian crisis,” but soon began making waves. Soon after, some of Seppelt’s sources stopped all communication. “This was a clear signal to me that these people who had been in contact with us had been warned that it might not be a good idea to talk to us again.”

The whistle-blowing athletes that appeared in the film are safe, Seppelt adds. “They’re in safe places, and they don’t regret anything of what they have done.”

Russia initially denied the allegations in the report and even accused Seppelt and his team of working for the German government and seeking to tarnish the country’s reputation. Those allegations failed to convince a Russian court, which in September rejected two lawsuits against Seppelt and ARD by Russia’s athletics federation and its ex-president, Valentin Balakhnichev.

While doping is not just a Russian problem or limited to athletics, Seppelt says it is worse in Russia than in most other countries, pointing out that “the doping culture, the doping tradition, is a remnant of the Soviet Union era.”

Seppelt describes the IAAF’s decision to suspend Russian athletes as “necessary and the right step” in order to set an example to other countries where doping is rampant. “You need pressure, you need sanctions, otherwise people will continue to work with doping substances as they have for decades.”

The challenge, Seppelt says, is to change a mentality and a structure that has supported and nurtured the doping culture. Russian athletes should therefore remain suspended during the Olympics as part of a tough and serious response, he adds. “It cannot be that you just exclude them for some competitions in winter, which are not very important. You have to react in a way which has a long-term effect.”