Kim R. Ordway, 33, formerly of the City of Tonawanda, was convicted Wednesday in Kansas on two counts of second-degree murder for killing his parents.
Ordway could face up to nine years in prison on each count.
He had been charged with first-degree murder and pleaded innocent by reason of insanity in the November 1993 killings of Clarence and Betty Ordway in their Stockton, Kan., home.
During the trial, jurors were told that, in the hours before the slayings, Ordway heard "voices" that told him he "had to kill" his parents "or rot in hell."
Clarence Ordway's body was found in the home. Betty Ordway's body was found in the trunk of a car in which her son was sitting outside his estranged wife's home in Kenmore, where he was arrested several days after the killings. Ordway could have served 40 years or more if he had been found guilty of first-degree murder, a charge that carries the element of premeditation.
If the jury had accepted the insanity plea, Ordway would have been sent to a state hospital for an indefinite period.
In a talk with Buffalo lawyer Thomas J. Eoannou in December 1993, Ordway said his voices told him that his parents would kill his children if he did not kill his parents. Eoannou testified Monday after Ordway waived his right to attorney-client privilege.
Eoannou said Ordway told him that he hit his mother on the side of the head with a two-by-four as she watched TV in the living room at about 7:30 p.m. Nov. 19, 1993.
As she screamed and fell to the floor, Ordway said, he shot her twice in the stomach with a shotgun loaded with "deer slugs." Then he went to his father, who was sleeping, and shot him twice in the back, he said.