A New Jersey man accused of killing his younger brother in a shocking and disturbing case has died in jail months after his arrest. Matthew Hertgen, a former college soccer player whose case drew national attention due to its violent details and discussions around mental illness, was found dead at the Mercer County Jail in an apparent suicide, according to reports.
His death comes shortly after a judge ruled that he was not legally responsible for his brother’s killing because of severe mental illness.
Matthew Hertgen Found Dead in New Jersey Jail
Authorities confirmed that 32-year-old Matthew Hertgen was found dead inside Mercer County Jail on May 8.
According to reports, investigators believe the death was an apparent suicide, though an official cause of death is still pending an autopsy.
Officials said Hertgen had previously attempted suicide shortly after his arrest earlier this year.
The Mercer County Prosecutor’s Office confirmed his death but has not released further details about the ongoing investigation.
Case Gained Attention After Brother’s Killing
Matthew Hertgen was facing murder charges connected to the death of his younger brother, 26-year-old Joseph Hertgen.
Authorities alleged the killing happened inside an apartment in Princeton, New Jersey, in February 2025.
Investigators claimed Matthew attacked Joseph using a knife and golf club during the violent incident.
He was also accused of killing a cat inside the apartment.
The case shocked many people due to the disturbing details revealed during the investigation.
Court Ruled He Was Legally Insane
In March, a judge reportedly ruled that Matthew Hertgen was not legally responsible for his brother’s death because he was suffering from severe mental illness.
A hearing had been scheduled to decide where he would receive treatment and supervision moving forward.
During court proceedings, forensic psychologist Dr. Gianni Pirelli testified that Hertgen experienced severe psychotic episodes and disturbing religious visions.
According to testimony, Hertgen believed he was seeing divine and apocalyptic visions and sometimes thought a “sacrificial murder” was necessary.
Family Reportedly Knew About Mental Health Struggles
Court documents showed that Matthew’s family had been aware of his mental health struggles for several years.
Investigators said his older brother, David Hertgen, told police that Matthew had been suffering from worsening psychotic behaviour and terrifying visions.
On the night of Joseph’s death, David reportedly warned Joseph through text messages that Matthew was experiencing troubling visions and asked him to reach out if he needed help.
Joseph reportedly replied, “Will do.”
Family Remembers Matthew in Obituary
Despite the tragic circumstances surrounding the case, Matthew’s obituary focused heavily on his battle with mental illness and the person he was before his condition worsened.
The obituary described him as a caring and loving person who enjoyed spending time with his family.
It also mentioned that he attended Wesleyan University, where he played soccer and earned a degree in microbiology and biochemistry before later working in senior finance roles.
His family said that despite his struggles, he showed sorrow, remorse, and repentance during his later years.
The obituary also encouraged donations to NAMI Mercer, a mental health nonprofit organisation that supports individuals and families dealing with mental illness.
Case Sparks Conversation About Mental Health
The deaths of both Matthew and Joseph Hertgen have led to wider discussions about severe mental illness, access to treatment, and family support systems during mental health crises.
The tragic case has left many people questioning whether earlier intervention or stronger mental health care could have helped prevent the violent events that unfolded.
As investigations into Matthew’s death continue, the case remains one of the most disturbing and heartbreaking criminal incidents reported in New Jersey this year.
