The 54-year-old was just 17 years into his life sentence at a prison in the northwestern city of Zhitomir when he died Tuesday, said Igor Andrushko of Ukraine's Penitentiary Service.
Onoprienko was convicted in 1999 of a killing spree that began in 1989 in which he would slaughter entire families, RIA Novosti said.
In 1989, he shot nine people in just over a month and fled, trying to seek asylum in Western Europe and Canada.
Unsuccessful, he returned to the Ukraine, where he began targeting families in small, remote villages.
Onoprienko would throw a brick through the window of a home and when the man of the family ran out to inspect, he would shoot him to death. He would then kill the wife and children with a knife to save on bullets, RIA Novosti said.
"Everyone was scared," said a resident in Bratkovichi, where 12 people were killed. "Several families would gather in one house to sleep, barricade [the doors], close the windows with plywood."
"Thank God he croaked at last -- let him go to hell," another resident of the village said.
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