Nikita Kamaev, the former head of Russia's anti-doping agency, has died, according to reports in Russia.
Kamaev resigned from his position at RUSADA in December following the doping scandal which has engulfed athletics in the country.
Russia was suspended from international athletics in November after the World Anti-Doping Agency (WADA) accused RUSADA of "state-sponsored" doping and corruption.
Ramil Khabriev, the agency's former director general, told Russian news agency Tass that Kamaev's death appeared to be caused by a heart attack.
"He complained of heart ache after a skiing session," said Khabriev.
"He has never complained about heart problems, at least to me. Maybe his wife knew about such problems."