A Emery County man who shot and killed his mother two years ago because he thought she was a demon, and moments later fatally shot his brother, has been sentenced to prison for up to life.
Seth Gordon Peterson, 26, was convicted in December by a 7th District Court jury of second-degree felony manslaughter in the November 2016 death of 45-year-old Susan Peterson — allegedly while the son was experiencing a methamphetamine-induced psychosis and believed his mother was a demon.
But the jury did not find Seth Peterson was intoxicated by drugs — or suffering from any hallucinations — about 30 seconds later, when he shot his brother, 23-year-old James Peterson.
In the brother’s death, jurors found Seth Peterson guilty of a harsher count of first-degree felony aggravated murder.
Defense attorney Rudy Bautista has said the two verdicts are inconsistent, and that he plans to explore options to get the aggravated murder conviction overturned.
On Wednesday, 7th District Judge George Harmond sentenced the defendant to 25-years-to-life in the brother’s death and one-to-15-years for killing his mother.
Seth Peterson also was found sentenced to prison terms on counts of attempted aggravated murder, aggravated robbery and failure to stop at the command of police. The judge ordereed all the sentenced to run concurrently.
The charges stem from a Nov. 2, 2016, altercation in which Seth Peterson shot his mother at a remote ranch in Carbon County.
Seth Peterson’s uncle, who witnessed the shooting, said he heard Seth Peterson say, “I just shot my mom in the f---ing face,” according to court documents,
Shortly afterward, James Peterson drove toward the mother’s body in a truck. The men’s uncle then heard a second gunshot before Seth Peterson drove away in the truck, leaving the brother fatally wounded.
Seth Peterson later approached the owner of the truck, Joseph Scott Feichko, pointed a rifle at his chest and said, “You have to help me hide two bodies.”
When Feichko didn’t comply, according to court records, Seth Peterson beat him with a crowbar, then fled in the truck.
Seth Peterson was arrested after police officers responded to reports of shots fired and saw him driving away from a farm about 7 miles west of Price, just off State Road 122. He led officers on a lengthy pursuit that ended after he crashed the vehicle.
At trial, Bautista presented evidence showing Seth Peterson had been using meth for four days straight. He was sleep-deprived and dehydrated when he killed his mother and brother, Bautista said, and was in a state of “meth psychosis.”
Seth Peterson thought that his mother and brother were being held captive and that he was confronting two demons, Bautista said.
“It’s not illegal to kill demons,” the lawyer said. “So if he thought he killed demons, he can’t be guilty of aggravated murder.
Seth Peterson had called police earlier that day, saying he was hallucinating and in danger. Police showed up at 2 p.m., Bautista said, and asked Seth Peterson when he last used meth. But he denied using drugs, and police called Susan Peterson at 4 p.m. to ask her to come take care of her son, then left the ranch.
Susan Peterson arrived and, by 5:30 p.m., had been shot dead.
Erik Peterson, one of Seth Peterson’s 14 siblings, has said that members of his family left the polygamous Latter Day Church of Christ, also known as the Kingston Group, gradually and for various reasons from 2013 through 2015.
Bautista has said that religious background influenced Seth Peterson’s hallucinations, Bautista said.
“His uncle testified that he believed Seth was possessed by Satan on the day of the shootings,” Bautista noted.
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