Cody Posey was accused of killing his father, stepmother and stepsister and hiding their bodies in a manure pile in 2004. The defense claimed the deaths were self-defense after he had suffered years of physical and mental abuse.
He was convicted of first-degree murder in the death of his stepsister, 13-year-old Mary Lee Schmid, whom he admitting killing so she couldn't tell on him. He was convicted of second-degree murder in the death of his stepmother, Tryone Posey.
The voluntary manslaughter conviction came from the death of his father, Paul Posey, who worked as the foreman for Donaldson's ranch near Hondo.
Posey also was convicted of four counts of evidence tampering. He hung his head and wept as the verdicts were read, and defense attorney Gary Mitchell offered consolation by putting an arm on the teen's shoulder.
Mitchell described years of physical and psychological abuse and said the flashpoint to the murders came when Paul Posey burned the boy with a metal welding rod after the teen refused to have sex with his stepmother the night before the slayings.
Posey could face life in prison on the first-degree murder charge. State District Judge Waylon Counts said an adjudication hearing would be scheduled within 30 days and remanded Posey into detention.
