Wyatt Testerman admitted killing Cheri Oliver while prosecutors rejected any sentencing agreement.
COVINGTON, Ky. — A Northern Kentucky murder case that once pointed toward an insanity defense is now headed to sentencing after Wyatt Testerman pleaded guilty but mentally ill in the killing of his grandmother, Cheri Oliver.
The plea, entered May 5 in Kenton County Circuit Court, settled the question of guilt but did not settle punishment. Testerman, 19, admitted murdering Oliver, 74, after police and prosecutors said he beat her inside an Erlanger home in October 2024. Prosecutors did not agree to a reduced sentence. Kenton County Commonwealth’s Attorney Rob Sanders said his office will ask for life in prison when Testerman returns to court July 7.
The phrase “guilty but mentally ill” now sits at the center of the case. It means Testerman has been convicted and can be sentenced for murder, while also becoming eligible for mental health treatment while serving the sentence. It is not the same as being found not guilty by reason of insanity. In court, Testerman said he understood the hearing, even as he described hallucinations and long-term drug use. The plea moved the case away from a trial that would have focused on criminal responsibility and toward a sentencing hearing focused on punishment.
Testerman’s attorney had previously explored an insanity defense. A defense expert later concluded that Testerman had antisocial personality disorder and was very likely in a psychotic episode tied to voluntary drug use. Prosecutors said his history of psychosis had been consistently linked to drugs. That finding narrowed the legal path for the defense because Kentucky’s insanity standard is not met simply because a defendant used drugs or had a drug-related episode. Testerman told the judge he had used acid for a long period before the killing.
The killing happened Oct. 8, 2024, at a home in the 100 block of Ridgewood Drive in Erlanger. Police said they were called around 2 p.m. for a reported assault involving family members. Officers found Testerman outside the residence and Oliver inside with severe head injuries. She was treated by paramedics and taken to the University of Cincinnati Medical Center, where she died. Detective Tom Loos later said an autopsy showed Oliver died from blunt trauma to the head.
Prosecutors said the evidence would have shown an attack that was recorded on a phone. They said Testerman positioned the device before pushing Oliver down and assaulting her. Court accounts described more than 40 punches, about 12 stomps and blows from a metal drinking tumbler. Investigators said the attack appeared unprovoked. The alleged video became one reason prosecutors were prepared to take the case to trial, where jurors could have been asked to view the recording and decide whether Testerman was criminally responsible.
During the plea hearing, Testerman gave the court a direct admission. He said he had abused acid and attacked Oliver without reason, striking her until she died. The statement did not answer all questions about motive, but it removed the main factual dispute over who killed Oliver. Prosecutors said Testerman had no agreement with them when he pleaded. That detail matters because a negotiated plea often includes a recommended sentence. Here, the commonwealth kept the right to seek life, and the defense kept the right to argue for less.
The evidence also includes witness accounts from inside the home. Police testimony placed Oliver’s ex-husband and Testerman’s mother at or near the scene. Loos said Testerman’s mother had arrived home and tried to call police. Other accounts said she attempted to stop the attack by hitting Testerman with a cane. Loos also testified that Testerman told detectives he had been watching a movie with his grandparents before the violence. Oliver’s ex-husband told investigators that Testerman had warned Oliver she would face consequences if she got out of a chair.
The first public police account called the matter an isolated family dispute and said there was no further threat. That statement answered neighborhood fears but could not capture the legal complexity that followed. Testerman was arrested, charged with murder and held at the Kenton County Detention Center. He first pleaded not guilty. Court appearances then tracked two questions at once: whether he committed the acts described by police and whether his mental state could alter the outcome. The May plea answered the first question and narrowed the second.
Sanders has signaled that the state will frame Oliver as a defenseless elderly victim and the attack as one of extreme violence. The sentencing record is expected to include the number of blows, Oliver’s age, the relationship between victim and defendant, the alleged recording and the witnesses who were unable to stop the assault. The defense is expected to emphasize Testerman’s age, substance abuse and mental health history. Judge Patricia Summe will have to decide how much weight to give those facts under Kentucky’s murder sentencing range.
The plea also spared a jury from deciding the case through graphic evidence. Sanders said the recording was among the most disturbing evidence he had seen. Still, the public record leaves major unknowns. No clear motive has been identified beyond the accounts of sudden violence and drug use. It remains unclear what Testerman’s prison mental health treatment would involve, where he would be housed after sentencing or how long he could remain in a prison hospital before serving the rest of any sentence in a traditional prison setting.
Currently, Testerman’s sentencing is scheduled for July 7. He faces 20 to 50 years or life in prison, and prosecutors have said they will ask Judge Patricia Summe to impose the maximum sentence.
Author note: Last updated May 25, 2026.