Prosecutors said they will seek life in prison after Wyatt Testerman pleaded guilty but mentally ill.

ERLANGER, Ky. — A 19-year-old Northern Kentucky man admitted in court that he killed his 74-year-old grandmother during an October 2024 attack at an Erlanger home, shifting the murder case toward a July sentencing instead of trial.

Wyatt Testerman pleaded guilty but mentally ill to murder in Kenton County Circuit Court on May 5 in the death of Cheri Oliver. The plea did not come with a sentencing deal, and Kenton County Commonwealth’s Attorney Rob Sanders said prosecutors still plan to seek the maximum punishment of life in prison. The case now turns on how Judge Patricia Summe weighs the plea, the mental health finding and the evidence prosecutors said would have been shown to jurors.

The attack happened around 2 p.m. on Oct. 8, 2024, in the 100 block of Ridgewood Drive, near Narrows Drive. Erlanger police were called for a reported assault involving family members. Officers found Testerman outside the home and Oliver inside with severe head injuries. Paramedics treated her at the scene before she was taken to the University of Cincinnati Medical Center, where she was pronounced dead. Detective Tom Loos later testified that Oliver was found lying in a pool of blood and that an autopsy determined she died from blunt trauma to the head.

In court, Testerman linked his actions to drug use but did not deny killing Oliver. “I had been abusing acid for quite some time,” he said, according to courtroom accounts. He also told the judge that he attacked his grandmother without reason and killed her by striking her repeatedly. Prosecutors said that statement was important because Testerman had earlier been expected to pursue an insanity defense. His guilty but mentally ill plea means the conviction remains a murder conviction, while the prison system is expected to make mental health treatment available during his incarceration.

Prosecutors described the evidence as unusually direct and violent. They said Testerman recorded the killing on a phone after placing the device in position. Court filings and police testimony described an assault in which Oliver was punched more than 40 times, stomped roughly a dozen times and struck with a metal drinking tumbler. Investigators said witnesses reported that Testerman became violent for no clear reason. Testerman’s mother and Oliver’s ex-husband were present at the home, and police said the mother tried to stop the attack by striking Testerman with a cane.

The family setting has remained central to the case from the first police response. Oliver was not a stranger to the accused attacker. She was his grandmother, and the home was described by police as the site of a family dispute that became deadly domestic violence. At an earlier hearing, Loos said Testerman told detectives he had been watching a movie with his grandparents before the assault. Loos also said Oliver’s ex-husband told investigators that Testerman warned Oliver she would face consequences if she got out of a chair. Prosecutors have not said that any action by Oliver caused the attack.

The plea followed months of legal movement after Testerman’s October 2024 arrest. He was 18 at the time of the killing and 19 when he changed his plea. He had originally pleaded not guilty after being charged with murder. The case had been headed toward trial, where jurors could have been shown the phone recording. Prosecutors said no plea bargain was reached, leaving the full sentencing range open. Under Kentucky law, murder can bring 20 to 50 years in prison or life, and prosecutors have said they will argue for the top end of that range.

Mental health questions remain part of the record but no longer appear likely to decide guilt. Testerman’s attorney had explored an insanity defense, but a defense expert later found that Testerman suffered from antisocial personality disorder and was very likely in a psychotic episode tied to voluntary drug use. Prosecutors said his history of psychosis had been linked to drug use, not a condition that met Kentucky’s legal standard for insanity. During the plea hearing, Testerman said he had experienced hallucinations but also said he understood what was happening in court.

Sanders called the killing among the most brutal cases he had seen and said the recording would have been difficult for jurors to watch. His office has framed the lack of a sentencing agreement as key to the next phase, because the guilty plea resolved the question of conviction but not punishment. Defense arguments at sentencing are expected to focus on Testerman’s age, mental health record and substance abuse. Prosecutors are expected to focus on Oliver’s age, the family relationship, the number of blows and the allegation that the attack was filmed.

The neighborhood where the killing occurred is a residential part of Erlanger, a Kenton County city in Northern Kentucky near Cincinnati. Police said after the attack that the incident was isolated and that there was no further threat to the public. That statement closed the public safety question but not the criminal case. The court record now centers on a family homicide in which witnesses, medical findings, police testimony and the alleged video all point to the same basic sequence: a domestic assault, a fatal head injury and an arrest at the scene.

For now, Testerman remains scheduled to be sentenced July 7 before Judge Patricia Summe. The next hearing will decide whether he receives a term of years or life in prison, with mental health treatment to occur inside the correctional system if the guilty but mentally ill judgment is accepted at sentencing.

Author note: Last updated May 25, 2026.