Grigory Rodchenkov, the former head of Moscow's anti-doping laboratory turned whistleblower, will be looking over his shoulder for the rest of his life, his lawyer said on Tuesday.
Russia was banned from the 2018 Pyeongchang Winter Games by the IOC on Tuesday, a decision praised by Rodchenkov.
His revelations of state-sponsored doping and cover-up at the Sochi 2014 Winter Olympics triggered investigations by both the World Anti-Doping Agency (WADA) and the IOC, which led to the ban.
His lawyer says this means he is in fear for his life.
"I hope the situation improves from here, but the Kremlin has proven to be a determined and difficult adversary for Grigory," said Jim Walden, Rodchenkov's lawyer.
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"I think the future ahead is hard to chart but for sure, without any doubt in my mind, I can say he knows he is going to be looking over his shoulder for the rest of his life."
Rodchenkov's account, first published in the New York Times, led to the establishment of Canadian lawyer Richard McLaren's independent report for WADA.
The IOC followed up with its own investigation, which confirmed "the systematic manipulation of the anti-doping rules and system in Russia."
While the IOC announcement vindicated Rodchenkov, he remains in hiding in the United States.
Last month, Russia's investigative committee said it planned to ask the United States to extradite Rodchenkov.
Two other senior former Russian anti-doping officials, Nikita Kamayev and Vyacheslav Sinev, died suddenly within weeks of each other in February 2016.
Walden said his client is also very concerned about his family in Russia, which authorities might use in an attempt to retaliate against him.
