A man who brutally murdered his younger brother and their family cat has been found dead in his jail cell. Matthew Hertgen, 32, was discovered at Mercer County Jail in New Jersey earlier this month, according to the Mercer County Prosecutor's Office. The cause of death has not been officially released, but reports indicate it was an apparent suicide.
Hertgen, a former soccer star at Wesleyan University, had attempted to take his own life shortly after his arrest in February 2025. In March of this year, a judge ruled that he was not criminally responsible for the death of his 26-year-old brother, Joseph, citing severe mental illness. The ruling deemed Hertgen legally insane.
Details of the Crime
The horrific incident occurred in their Princeton, New Jersey, apartment. Hertgen stabbed Joseph with a knife and beat him with a golf club. He also set the family cat on fire before calling 911 to report a body. When police arrived at the bloody scene, Hertgen was arrested without incident.
During the attack, Hertgen also ripped out Joseph's eye and consumed it, according to the New York Post. The gruesome details shocked the community and drew national attention to the case.
Mental Health History
Forensic psychologists testified that Hertgen had a documented history of escalating psychotic behavior, including religious, supernatural, and apocalyptic visions. He was diagnosed with schizophrenia. His older brother, David Hertgen, told investigators that Matthew had been experiencing severe mental illness for five years and was extremely distressed on the day of the murder.
The night of the killing, David texted Joseph warning him that Matthew was having visions, to which Joseph replied, “Will do.”
Legal Outcome
Hertgen faced charges of first-degree murder, weapons offenses, and animal cruelty. However, due to his insanity ruling, a hearing was scheduled to determine his future custody, which likely would have involved long-term commitment to a state psychiatric hospital. His death has now rendered those proceedings moot.
Obiturary and Remembrance
Hertgen’s obituary acknowledged his mental health struggles, describing him as a caring person who struggled with severe mental health issues. It stated that he expressed sorrow, remorse, and repentance and departed with the love and forgiveness of his family.
The case highlights the tragic intersection of severe mental illness and violent behavior, leaving a community and family grappling with loss and unanswered questions.
