CALDWELL, Idaho (Scripps News Boise) — An Idaho man charged with killing his daughter in their home on Monday allegedly confessed to police during an interview.
Delbert Cornish was arrested in Mountain Home on Monday, transferred to Canyon County custody on Tuesday, and was arraigned in Canyon County Court on Wednesday afternoon, where he was appointed a public defender. He is currently being held without bail.
Delbert Cornish appears in court via video conference. (Scripps News Boise)
Court documents obtained by Scripps News Boise reveal many details about the case, including an alleged confession.
The records say Cornish told a detective, “I’m not gonna lie, I did it, dude.” A probable cause affidavit explains Cornish previously planned to kill all of his children and then himself.
Documents say Cornish began to cry while being questioned, and told officers he was an alcoholic who struggles with depression. During the interview, Cornish said he bought a gun last fall and came up with the idea to kill all three of his children and then himself, but the plan was ruined a few months ago when his oldest son violated parole and was sent back to prison.
Cornish lived with his brother and two of his children in the Caldwell home where the murder took place, just a few blocks from the Canyon County jail.
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The Canyon County Coroner identified the 18-year-old victim on Tuesday as Hope Cornish. Family members say she went by “Onyx” and that Cornish adopted her many years ago.
Court documents show Cornish told detectives he lost his job two weeks ago, but was keeping it a secret from his brother, and felt he couldn’t hide it much longer. When he woke up on Monday, he told his brother, “Today was the day,” but did not tell him what that meant.
He walked officers through his day, including how he contemplated when and how to kill Onyx. While he stood outside her bedroom door trying to decide what to do, she happened to open the door. He told officers he shot her in the head, then stood there for 20 minutes watching her “gasp for breath.”
Cornish began to cry out loud and told the detective, “I’m a piece of s***, man. I’m not going to lie, I did it.”
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Court documents say that after killing Onyx, Cornish covered her body with a Pride flag as a way to honor her, and then shot and killed her cat. He then went into a “fit of rage” and punched holes in the walls around the house, and swung a hatchet into Onyx’s bedroom door. He then wrote a confession and suicide note, drank bourbon, and watched TV until his son came home from school.
When Cornish’s son got home, he told the teen he had killed his sister and tried to convince him to check on her. Documents say Cornish then shot the floor and pointed the gun at his son while blocking him from leaving the house. The son was ultimately able to disarm his dad, leave the house, and call 911.
Cornish then drove to his ex-girlfriend’s house in Mountain Home, where he was taken into custody Monday night.
Cornish will be back in court for a preliminary hearing on September 3.
This story was originally published by Scripps News Boise, an E.W. Scripps Company.
