HOPEWELL TOWNSHIP, N.J. (Court TV) — Days before he was due to return to court for a review of his mental status, Matthew Hertgen was found dead in his jail cell.
Matthew Hertgen appears in court for his murder trial on March 18, 2026. (Court TV)
Matthew Hertgen, 32, was found dead in his jail cell at the Mercer County Correction Center on May 8, jail officials confirmed to Court TV. An autopsy report has not yet been completed, but his death is being treated as an apparent suicide.
At a one-day trial in March, Judge Robert Lytle found Matthew Hertgen not guilty by reason of insanity in the death of his younger brother, Joseph Hertgen. Matthew Hertgen had been experiencing psychotic delusions when he used a knife and a golf club to attack his brother. The victim was found with a large pool of blood around his head and torso; his chest cavity was exposed and his right eyeball was missing. Investigators said Matthew Hertgen also beat and stabbed a cat before setting the animal on fire.
Matthew Hertgen told his family, doctors and his defense team that he had been suffering from “visions” at the time of the incident. Dr. Gianni Pirelli, a clinical and forensic psychologist, was the only witness who testified at the trial. He told the courtroom that the defendant had “one of the most severe mental illnesses that I’ve seen.” While Pirelli said that Matthew Hertgen was willing to talk to him, “he believes the spirit that overtook him in 2021 is basically too powerful for any medications or mental health treatment.”
Matthew Hertgen was scheduled to be back in court on May 29 for a hearing intended to review his mental health status and address next steps.
An obituary published online says Matthew Hertgen “is remembered as a caring and loving person” who graduated from Wesleyan University before working for a telecom company. “During his later years, Matthew struggled with profound mental health issues; yet he expressed sorrow, remorse, and repentance in many ways,” the obituary says. “He departed with the love, friendship and forgiveness of his family and the eternal hope of salvation.”
The obituary requests that visitors consider donating to the National Alliance on Mental Illness of Mercer County, N.J.
