A Princeton man who butchered his younger brother and ate his eyeball before setting the family cat on fire has been found dead inside his New Jersey jail cell.
Matthew Hertgen, the former Wesleyan University soccer player whose horrifying case stunned the nation last year, was discovered unresponsive inside Mercer County Jail on May 8, according to the Mercer County Prosecutor's Office.
Officials have not yet released a formal cause of death but the New York Post reports that the death is being treated as a suicide.
The 31-year-old had already attempted to take his own life once before while behind bars as he tried to hang himself in his cell just days after his February 2025 arrest.
He was cleared of his brother Joseph Hertgen's murder by reason of insanity by Mercer County Superior Court Judge Robert Lytle in March.
Hertgen was accused of brutally killing his 26-year-old brother during a psychotic episode before mutilating the corpse in a scene investigators described as 'horrifying.'
Despite the brutality of the killing, Matthew's family attempted to remember him through the lens of his mental illness rather than solely the violence that defined his final years.
'During his later years, Matthew struggled with severe and profound mental health issues; yet he expressed sorrow, remorse, and repentance in many ways,' his obituary stated.
Matthew Hertgen, 31, accused of carrying out a gruesome cannibalistic killing in Princeton, New Jersey was found dead inside Mercer County Jail on May 8 in an apparent suicide
Joseph Hertgen, 26, was found dead inside the brothers' luxury apartment in Princeton in February 2025
Police said Joseph was found lying in a pool of blood beside a knife after officers responded to a 911 call reporting a fire and a dead body in Princeton on February 22, 2025.
Join The Crime Desk
Keep up to date with the most chilling cases and investigations by signing up for free HERE
Prosecutors said the crime unfolded inside the brothers' luxury apartment near the prestigious Ivy League university.
Investigators described how Matthew used a knife and golf clubs to beat and stab his younger brother to death before tearing out one of his eyes and consuming it.
Authorities also accused him of killing the family cat and setting the animal on fire during the rampage.
The case immediately drew national attention not only because of its gruesome details, but because the Hertgens appeared to come from a picture-perfect upper-middle-class background.
The brothers were raised in Toms River, New Jersey, where they grew up in a wealthy family headed by tech executive David Hertgen, president and CFO of internet provider WiLine Networks.
The family later relocated to the upscale Michelle Mews apartments in Princeton, where rents reportedly ranged from $6,000 to $7,000 per month.
Joseph was remembered by loved ones as warm and kindhearted. He graduated from University of Michigan with a business administration degree before going on to work in finance.
Hertgen had previously attempted to hang himself in jail just days after his February 2025 arrest for murdering his younger brother Joseph and then earing his eyeball
One day before the brutal murder, heavily bearded Matthew posted a chilling selfie laying expressionless on the floor next to a cat toy. He was also accused of setting the cat on fire
Matthew, pictured, became obsessed with apocalyptic ideas and convinced himself that a 'sacrificial murder could save' the world
'He was such a kind person, had a great love of life and his smile brightened every room,' his obituary read.
The tribute praised Joseph's love of sports, chess, ping pong and travel - but made no mention of Matthew.
Matthew Hertgen, meanwhile, had reportedly battled schizophrenia and severe mental illness for years before the killing.
According to testimony presented during court proceedings, Hertgen suffered from elaborate delusions and believed he was experiencing divine visions connected to the apocalypse.
Forensic psychologist Dr Gianni Pirelli testified that Hertgen believed at different times he was Jesus Christ, God, the Anti-Christ, or possessed multiple souls.
'Anytime he closes his eyes, he's seeing tremendous visions,' Pirelli testified in court.
The psychologist said Hertgen became consumed by apocalyptic thinking and eventually convinced himself that a 'sacrificial murder could save' the world.
Pirelli also testified that Hertgen became fixated on themes contained in Swiss psychiatrist Carl Jung's 'Red Book,' specifically a chapter titled The Sacrificial Murder.
'It kind of clicks for him and he puts two and two together,' Pirelli testified.
Brother, Joseph, graduated from the University of Michigan with a business administration degree
The pair also had a third brother, David Jr., who works for their father's company. Pictured, Joseph, left, David Jr., center and Matthew, right
Joseph, 27, was. beaten to death with a golf club and a knife inside the family's luxury Princeton apartment on February 22, 2025
Court records showed Hertgen's mental health struggles dated back years, with relatives and investigators tracing the beginning of his decline to his time living in New York City around 2021.
At his first court appearance after the killing, Hertgen appeared virtually wearing a green suicide-prevention vest and looked visibly dazed while facing murder and animal cruelty charges.
Surveillance footage later shown during proceedings reportedly captured Joseph attempting to restrain his older brother moments before the fatal attack escalated.
In March 2025, Mercer County Superior Court Judge Robert Lytle ruled Hertgen not guilty by reason of insanity after experts concluded he was suffering from severe schizophrenia during the killing.
That decision meant Hertgen avoided a traditional murder conviction and instead faced indefinite confinement in a psychiatric institution.