Vladimir Rodionovich Klitschko, who raised his sons, Wladimir and Vitali Klitschko, to become heavyweight champions, died Wednesday after a long illness in Kiev, Ukraine. He was 64.
The former colonel in the Soviet Union's air force died from lymph node cancer, according to the brothers' management team.
Vladimir Rodionovich Klitschko was stationed near Chernobyl during the 1986 nuclear disaster and participated in the immediate cleanup of the reactor's meltdown. His illness was linked to the disaster that sickened many who lived in the region.
"When the first message came through the only thing it said was that something bad had happened. The alarm was raised," he said in "Klitschko," a documentary about his sons' lives that was recently released n Europe. "I was the leader of an air force unit that was immediately relocated to the scene of the incident.
"From the very beginning, the government tried to cover up the truth and play down the situation. We were given the impression that it wasn't all that serious. Those who were able to leave Kiev took the opportunity to do so, but if you are a soldier you have to fulfill your duties."
Klitschko, who did not attend his sons' fights, had been ill for several years. Although he was unable to travel recently, he lived long enough to watch Wladimir Klitschko's lopsided title unification victory against David Haye on July 2.
"Our father spent a lot of time at Chernobyl, and Chernobyl got him, too, in the end. The doctors said, 'It's the result of Chernobyl. Cancer,' " Vitali Klitschko said in the documentary.
Klitschko is survived by his wife, Nadeshda, his sons and three grandchildren.
Dan Rafael is the boxing writer for ESPN.com. Follow him on Twitter @danrafaelespn.