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Utah man sentenced for killing mother and brother he believed were 'demons'

By Annie Knox, KSL | Posted - Apr 24th, 2018 @ 7:11pm


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SALT LAKE CITY — A judge has sentenced a Ferron man to up to life in prison for shooting and killing his mom and brother, over protest from defense attorneys who said a jury's split verdict in the case makes no sense.

Jurors in December found the death of Seth Gordon Peterson's mother was manslaughter, a second-degree felony, but when Peterson killed his brother 30 seconds to a minute later, it was aggravated murder, a more severe first-degree felony.

Peterson's attorney has said he believes the same standard regarding Peterson's state of mind at the time should apply to both killings and the harsher conviction should not be allowed to stand.

But at a sentencing hearing Wednesday in 7th District Court in Price, Judge George Harmond sentenced Peterson, 26, to serve at least 25 years and up to life in prison for his brother's murder, with a sentence of one to 15 years running concurrently for his mother's death.

Peterson was originally charged with two counts of aggravated murder, a first-degree felony and potential capital offense, for the deaths of his mother, Susan Peterson, 45, and his brother, James Peterson, 23. Prosecutors determined earlier in the case they would not pursue the death penalty.

Prior to the sentencing, prosecutors said evidence in the case supported the distinct verdicts, arguing in court documents that the way Peterson behaved was "consistent with someone who had become angry, committed crimes, tried to eliminate witnesses and then tried not to get caught by police."

In February, Peterson's attorney, Rudy Bautista filed a motion arguing the jury's determinations were too inconsistent for slayings that took place less than a minute apart. He wrote that "this verdict makes no sense and is an extremely improbable finding," and questioned whether the jury understood its role.

But Jeremiah Humes, deputy Carbon County attorney, wrote in a response that there were several "rational, within reason and not inconsistent" ways the jury could have reached the different verdicts, including the possibility they found that Peterson was hallucinating while killing his mom but the hallucination halted after that and he realized what he'd done, or that the jury thought some leniency was appropriate.

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Peterson was experiencing "meth psychosis" and believed he was facing two "demons" when he killed the two family members on Nov. 2, 2016, in a field near a farmhouse outside Hiawatha, Carbon County, according to his attorneys.

A search warrant revealed he was paranoid in the days before the killings, believing police were following him and his phone was bugged.

Susan Peterson was shot dead when she went to the farmhouse to pick him up, according to prosecutors. When James Peterson got out of the truck to check on his mother, he was killed as well.

After the shootings, Seth Peterson drove off in the truck and approached the man who owned it, telling him he had killed two demons and saying "you have to help me hide two bodies," while pushing a rifle into the man's chest, the charges state. When the man resisted, Peterson hit him with a crowbar, injuring his arm.

Peterson's uncle also testified that he believed Peterson was possessed by Satan the day of the shootings, his attorney wrote in court documents.

Last week, the judge also issued concurrent sentences for Peterson's other convictions, including attempted aggravated murder and aggravated robbery, both first-degree felonies, and failure to stop at the command of police, a third-degree felony.

He recommended Peterson be considered for substance abuse treatment.

Correction: An earlier version of this story stated Seth Peterson hit his uncle with a crowbar. The man he hit was not his uncle, but the owner of a truck Peterson was driving.

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Updated: Wednesday August 15, 2018 5:05 am