CANYON COUNTY, Idaho (Court TV / Scripps News Idaho) — A father accused of killing his daughter and threatening his son emotionally admitted his crimes in a Canyon County courtroom Wednesday.
Delbert Cornish appeared in court to plead guilty to murder on Nov. 12, 2025. (Court TV)
Delbert Cornish formally pleaded guilty to first-degree murder for the Aug. 18, 2025 shooting death of his daughter, Hope “Onyx” Cornish. In a tearful courtroom confession, Cornish told the judge, “I pulled the trigger. I shot my daughter.”
When asked by the judge if he understood what he was doing when he fired the 9-millimeter handgun, Cornish responded, “Yes.”
Prosecutors say Cornish also shot and killed Onyx’s pet cat during the same incident and later threatened his teenage son, Lucian, who managed to wrestle the gun away and flee the home to call for help. Cornish also pleaded guilty to assault with intent to kill and animal cruelty.
First-degree murder in Idaho carries a mandatory sentence of life in prison without the possibility of parole. The judge has scheduled sentencing for Jan. 28, 2026, setting aside four hours for victim impact statements and testimony.
Onyx’s mother, Crystal Thompson, described hearing Cornish admit to the crime as devastating.
“That was hard. That answer was really—I don’t know. It’s like a truck hit me, just to hear him say it,” she said. “It’s made it all the more real, and I’m really struggling right now with that.”
Despite the trauma, Thompson says Lucian has turned to music to process his grief and is planning to give a victim impact statement at his father’s sentencing.
“He wrote a song, actually, and he’s writing an album… it’s so emotionally raw,” she said.
Lucian plans to deliver a victim statement at his father’s sentencing.
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