Casper police detectives will testify in an upcoming murder trial that Andrew Steplock went looking for his father after he shot and killed his mother in February.

Steplock is charged with first- and second-degree murder, aggravated burglary and possession of a deadly weapon with unlawful intent for the alleged Feb. 26 shooting death of his mother.

He has pleaded not guilty and not guilty by reason of mental illness to the charges.

Natrona County District Court Judge Daniel Forgey approved an August motion to allow Casper police detectives to testify that Steplock told them that after he shot Deborah Steplock in her home, Andrew Steplock went looking for his dad and was going to shoot him too.

"This evidence goes directly to (Andrew Steplock's) state of mind when he was in the house at the time of the charged homicide," Assistant Natrona County District Attorney Kevin Taheri writes in the motion. "It helps the state prove motive, intent and malice."

Forgey also approved a motion allowing the testimony of two women who said Deborah Steplock told them she replaced Andrew Steplock's key on his keyring.

The affidavit alleges Steplock tried to enter the home through the front door at 1 a.m. the morning of the alleged murder, but his key didn't work. Instead, he broke through a back door.

Though still in custody, Steplock will appear unshackled and in normal attire for his trial after Forgey approved a third motion on Friday.

According to an affidavit of probable cause, Casper police were called to a home at 10th and Center Streets at roughly 1 a.m. Feb. 26. When they arrived, they found Steplock's mother, Deborah Steplock, with a gunshot wound to her head.

Wyoming Division of Criminal Investigation agents assisted with the investigation.

Steplock was arrested at 11 p.m. that day in northern Colorado after authorities tracked his cell phone and found him sleeping in his mother's car at a truck stop.

Speaking with detectives, Steplock allegedly said that he walked up to his mother, pointed his gun at her face and shot her. Steplock allegedly said that he went into the home to steal money.

The trial is expected to last five days and will begin November 18.