Preppy Princeton killer who slayed brother and ate his eyeball found dead in jail cell

The preppy Princeton cannibal killer — who was determined to be not guilty by reason of insanity — was found dead in his New Jersey jail cell in an apparent suicide.

Matthew Hertgen was found dead at Mercer County Jail May 8, the Mercer County Prosecutor’s Office told NJ.com, which revealed the death Friday. An official cause of death has not been released.

He previously attempted to hang himself in his Mercer County Jail cell a week after his February 2025 arrest.

Hertgen, 31, was found not criminally responsible for his brother’s murder by reason of insanity by Mercer County Superior Court Judge Robert Lytle on March 19.

The former Wesleyan soccer player ripped out his little brother’s eyeball and devoured it after stabbing and beating him to death with golf clubs in their ritzy apartment in February 2025.

Hertgen also set the family cat on fire after his horrific slaughter of his 26-year-old brother Joseph.

Joseph’s corpse was found by cops lying in a pool of blood beside a bloody knife, after the twisted rampage, police officials said.

Surveillance footage shown at Hertgen’s trial showed him tackling Matthew to the ground and assaulting him.

The deranged cannibal suffered from “prophetic and divine visions,” according to forensic psychologist Dr. Gianni Pirelli, and was found not guilty by reason of insanity.

Pirelli testified that Hertgen had been diagnosed with schizophrenia and that he believed himself at various times to be Jesus Christ, anti-Christ, God or to have multiple souls.

“Anytime he closes his eyes, he’s seeing tremendous visions,” Pirelli said.

He also believed that the world was on the brink of the apocalypse, and only a “sacrificial murder could save it,” the doctor testified.

He was also influenced by a chapter in Swiss psychologist Carl Jung’s “Red Book” entitled “The Sacrificial Murder.”

“It kind of clicks for him and he puts two and two together,” Pirelli said.

Hertgen’s mental health problems began when he was living in New York City in 2021.

He had an idyllic childhood and grew up with his brothers in a tony $1.1 million home in Toms River before his family relocated to the luxe Michelle Mews apartments.

His family remembered the delusional maniac as a “caring and loving person” in his obituary.

“During his later years, Matthew struggled with severe and profound mental health issues; yet he expressed sorrow, remorse, and repentance in many ways,” the obituary stated.