A man who cannibalized his younger brother during a psychotic episode has been found dead in his prison cell. Matthew Hertgen, 31, 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.
Details of the Crime
Hertgen was accused of brutally killing his 26-year-old brother, Joseph, on February 22, 2025, inside their luxury apartment in Princeton, New Jersey. Investigators described how Hertgen used a knife and golf clubs to beat and stab his younger brother to death before tearing out one of his eyes and eating it. He was also accused of killing the family cat and setting the animal on fire.
Surveillance footage shown during proceedings reportedly captured Joseph trying to restrain his older brother moments before the attack.
Legal Outcome
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.
Forensic psychologist Dr Gianni Pirelli told the court that Hertgen believed at different times he was Jesus Christ, God, the Anti-Christ, or possessed multiple souls. The expert said Hertgen convinced himself that a ‘sacrificial murder could save’ the world.
History of Mental Health Issues
Hertgen reportedly battled schizophrenia and severe mental illness for years before the killing. His obituary said that ‘Matthew struggled with severe and profound mental health issues’ in his later years, adding: ‘Yet he expressed sorrow, remorse, and repentance in many ways.’ It continued: ‘He departed with the love, friendship and forgiveness of his family and the eternal hope of salvation.’
The former university soccer player had attempted to take his own life just days after his arrest in February 2025.
Family Background
The brothers grew up in a wealthy family in New Jersey before moving to upscale Michelle Mews apartments in Princeton. Joseph’s obituary at the time of his death paid tribute to a ‘kind person’ with ‘a great love of life’ and a ‘smile that brightened every room’.
The gruesome details shocked the US, in particular because of the family’s picture-perfect upbringing.
