A Kentucky man admitted Tuesday to brutally killing his grandmother in an unprovoked attack, pleading guilty but mentally ill in court.

Wyatt Testerman, 19, entered the plea to murder, which allows access to mental health treatment while in prison under state law.

He entered the plea without an agreement from prosecutors, and Kenton County Commonwealth Attorney Rob Sanders said his office will seek the maximum sentence of life in prison, The Cincinnati Enquirer reported.

Prosecutors said Testerman recorded a video of the October 2024 attack on his 74-year-old grandmother, Cheri Oliver, inside her home.

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The video allegedly shows Testerman setting up a phone to record before shoving Oliver to the floor and beating her.

At one point, he stopped to check her pulse and said, “How the [expletive] is she still breathing?”

According to court filings, Testerman struck Oliver more than 40 times, including with a metal cup, and stomped on her about a dozen times.

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Police found Oliver unconscious in a pool of blood. She later died from blunt force trauma to the head, according to the report.

Testerman’s mother told investigators she witnessed the attack and tried to stop him.

Another witness told police Testerman had earlier accused Oliver of being “suicidal and a terrorist” and warned her to stay seated or “suffer the consequences.”

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In court, Testerman said he had been struggling with substance abuse.

“I had been abusing acid for quite some time,” he said. “Without reason on that date, I attacked my grandmother, striking her numerous times and killing her.”

Testerman had been expected to pursue an insanity defense when his trial was set to begin May 12, but a defense expert later determined he suffers from antisocial personality disorder, his attorney said.

According to the report, Testerman told the judge he was experiencing hallucinations in the courtroom but acknowledged he understood the proceedings.

He faces 20 years to life in prison and is scheduled to be sentenced July 7.