CANYON COUNTY, Idaho (Scripps News Boise) — A lawyer representing Delbert Cornish , the Caldwell father charged with murdering his 18-year-old daughter, Onyx Cornish, in August, told a Canyon County judge on Tuesday that his client plans to plead guilty.

Delbert Cornish appears in court for a hearing on Oct. 14, 2025. (Victoria Rodriguez/Scripps News Boise)

Cornish is charged with first-degree murder, assault with intent to murder, use of a deadly weapon in the commission of a felony, and animal cruelty. Police say that after Cornish killed Onyx, he shot and killed her cat.

Canyon County neighborhood reporter Victoria Rodriguez was in court for Cornish’s arraignment on Tuesday and spoke exclusively with the victim’s mother, who considers the guilty plea a major relief for her surviv

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