Brother Found Not Guilty By Reason Of Insanity In Killing Of Toms River Grad

TRENTON, NJ — A former Toms River man who killed his brother with a golf club and cut out his eyeball in their Princeton home has been found not guilty by reason of insanity.

Matthew Hertgen, 32, was ruled legally insane in the killing of Joseph Hertgen, 27, during a bench trial before Mercer County Superior Court Judge Robert Lytle on Wednesday — a conclusion that prosecutors themselves said they could not contest.

Lytle agreed with mental health experts from both sides that Matthew Hertgen, who was charged with first-degree murder, weapons offenses and animal cruelty, was legally insane at the time he killed Joseph on Feb. 22, 2025.

"In his delusional state, the act was not wrong in the ordinary moral sense — it was required," Lytle said from the bench.

"It's the state's position the defendant has established the insanity defense by preponderance," Mercer County Assistant Prosecutor Tim McCann said. "It's my position the state concedes, and really can't contest that at this time."

The brothers, who grew up in Toms River, both played soccer at and graduated from Toms River North, Matthew in 2011 and Joseph in 2016. Both went on to college soccer careers, Matthew at Wesleyan and Joseph at the University of Michigan.

Dr. Gianni Pirelli, a clinical and forensic psychologist who evaluated Matthew Hertgen and reviewed his records, testified that Hertgen is schizophrenic and has struggled with severe mental illness since 2021.

"He believes that the spirit that overtook him in 2021 is basically too powerful for any medications or mental health treatment that would come about," Pirelli testified. "Anytime he closes his eyes, he's seeing tremendous visions."

Pirelli also told the court that Hertgen had been operating under apocalyptic religious delusions at the time of the killing. "He was also believing that he was Jesus and there was going to be an apocalypse," Pirelli said.

According to court records, Matthew Hertgen spent the evening of Feb. 22, 2025, with another brother, identified only as "D," who later told investigators Matthew had been "distressed, despondent, and experiencing terrifying visions" throughout the day. D dropped Matthew off at the apartment around 10 p.m. and briefly met Joseph there before leaving.

At 10:10 p.m., D texted Joseph warning him that Matthew was struggling with "his visions" and to reach out if he needed help. Less than an hour later, at 11:16 p.m., Hertgen called 911 to report a fire and a body inside the home — telling dispatchers his brother had been dead on the floor for 30 to 40 minutes. When asked how Joseph was injured, he said, "I'm not gonna go into any more details right now."

Officers arriving at the scene found Joseph Hertgen on the floor surrounded by a large pool of blood. He had suffered severe blunt force trauma to the back of his head, a large laceration to his chest and abdomen that exposed the chest cavity, and lacerations to his right eye — his right eyeball was not visible. A golf club was found on the floor near the body. On the dining table, police found a cup and utensils coated in what appeared to be blood.

In the living room, officers found the family's cat dead on an ottoman. The animal had been beaten, stabbed and set on fire.

Hertgen told police he had "gone into a fit of madness, maybe like forty minutes ago." He never denied his role in his brother's death.

Joseph Hertgen's University of Michigan soccer biography noted he earned honors at Toms River North, including being named to the New Jersey Central II All-State team, Shore Conference First Team in the A South division and Toms River North's Offensive Player of the Year and MVP for his senior season. His collegiate career was hampered by injuries but he earned academic honors while being on the team. A tweet from the Michigan men's soccer team account in 2019 showed him smiling and laughing with a teammate.

Joseph was an analyst at Locust Point Capital and had been there since December 2023, according to his LinkedIn profile. He had worked in Dallas after graduating from Michigan with a degree in finance.

Matthew Hertgen's biography on the Wesleyan University men's soccer did not say what he majored in while he was there. His Facebook timeline includes smiling photos from his time in college and a pair of untitled poems that speak of heartache, loss and an inability to break free from the source of the pain.

Because of the not guilty by reason of insanity verdict, Matthew Hertgen will remain in custody until sentencing May 1, at which point he is expected to be committed to a psychiatric facility.