FOR IMMEDIATE RELEASE
January 28, 2026
Delbert Cornish Sentenced to Life Without Parole for Murder of 18-Year-Old Onyx Cornish and Attempted Murder of 15-Year-Old Lucien Cornish
Caldwell, Idaho — Delbert Cornish was sentenced today by Third District Judge Gabriel McCarthy to life in prison without the possibility of parole for the August 18, 2025 murder of 18-year-old Onyx Cornish and the attempted murder of her 15-year-old brother, Lucien Cornish. Cornish was charged with first degree murder, attempted murder, and animal cruelty stemming from a violent rampage that also included the shooting of Onyx’s pet cat.
The Canyon County Prosecutor’s Office was represented by Chief Deputy Ingrid Batey and Deputy Prosecutor Stephanie Morse. Cornish was represented by defense attorney Erik Ellis.
In addressing the Court, Batey described the defendant’s actions as “senseless, cruel, cowardly, and callous,” and asked the Court to impose a sentence of life in prison without the possibility of parole. “Delbert Cornish should wake up behind bars every day for the rest of his life,” Batey said. “That still isn’t enough, but it’s the closest this Court can get to true justice.”
Ellis asked the Court to impose a 25-year fixed sentence, citing Cornish’s struggles with depression and suicidal ideation. Judge McCarthy ultimately agreed with the State and sentenced Cornish to life without the possibility of parole, describing the crime as “an act of pure evil.” In his final remarks to a packed courtroom, Judge McCarthy stated, “If there’s a God, perhaps God will have mercy on his soul. But the State of Idaho does not.”
“I want to thank the Caldwell Police Department for their diligent work on this case, as well as the Canyon County Sheriff’s Office and Canyon County Coroner’s Office,” Canyon County Prosecutor Chris Boyd said. “The Defendant’s actions were unthinkable and horrific, and he deserves to die in prison. I appreciate Judge McCarthy’s wise and thoughtful sentence, as well as his compassion for the victims in Court.”
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For more information, please contact our Prosecuting Attorney’s Office at (208)-754-7391
