An Ohio teenager meticulously plotted the murder of his neighbor over several months before carrying out the act and later boasting about it online, according to law enforcement officials.

The boy, who recently turned 14, admitted guilt to charges including aggravated murder, aggravated burglary, and strangulation as part of a plea bargain with the prosecution. Due to his young age, his identity remains undisclosed, as reported by Cincinnati’s ABC affiliate WCPO.

The tragic events unfolded in the early hours of February 2 when Sheila “Denise” Tenpenny was at her residence on the 3900 block of Germania Street in Fairfax, a suburb near Cincinnati. While she was in bed, the teenager broke into her home, inflicted blunt-force injuries, and ultimately strangled her to death.

Despite the fatal outcome, Tenpenny resisted fiercely. The Ohio Attorney General’s Office noted that the suspect likely sustained facial or hand injuries during the struggle. Investigative efforts confirmed the perpetrator was male.

Upon arriving at the scene, authorities described the 64-year-old woman’s death as “suspicious.” Evidence collected included the boy’s hair clutched in Tenpenny’s hands, his DNA under her fingernails, and facial scratches that left his blood at various points in the home.

Prosecutors revealed that after leaving the scene, the teen took to social media, posting a chilling message: “This one was a fighter.”

It was not uncommon for the boy to be on the internet with killing on his mind, authorities said. He planned the murder for months, researching online and asking ChatGPT how to “choose the perfect victim,” how to strangle someone, and how to “defeat a police interrogation,” local NBC affiliate WLWT reported.

Ohio Bureau of Criminal Investigation Agent David Ward said that in his 20 years of working violent crimes, he’s never seen someone “of this age commit this type of crime.”

“And to add to that the premeditation of the offense is just chilling to me,” Ward said, per WCPO. “As the investigation went on and continued, his social media communications with individuals … there were several other communications that are very disturbing.”

“He made mistakes. He left his DNA; he tried to clean up the crime scene with items that wouldn’t have been successful,” the agent added. “It was good luck for us that he did make those mistakes, but in the future, is he going to learn from those mistakes? That’s what I’m concerned about.”

As part of the plea deal, the boy will reportedly be held at the Ohio Department of Youth Services until he turns 21, the oldest age that the agency can hold a juvenile convicted of a crime.

Tenpenny is remembered as having been “a beacon of light who touched the lives of many with her kind heart, unwavering resilience, and exceptional humor, leaving behind a legacy filled with valuable lessons and unforgettable memories that will continue to inspire those who were fortunate enough to know her.”