A former Wesleyan University soccer player who was found not guilty by reason of insanity after brutally killing his younger brother in a gruesome attack has died in an apparent suicide inside his prison cell, according to reports.

Matthew Hertgen, 31, was found dead in his cell at the Mercer County Jail in New Jersey on May 8, the Mercer County Prosecutor’s Office confirmed to NJ.com. An official cause of death has not been released, and an autopsy report is pending.

The death came less than two months after a Mercer County judge ruled Hertgen was not criminally responsible for the February 2025 killing of his 26-year-old brother, Joseph Hertgen, at the brothers’ Princeton apartment.

Investigators said Hertgen stabbed and beat his younger brother to death with knives and golf clubs before mutilating the body, ripping out one of Joseph’s eyeballs and eating it. He also set their cat on fire during the attack.

Hertgen then called 911 to report a body inside the home, opened the door for responding officers, who discovered Joseph lying in a pool of blood beside a knife, and arrested Hertgen, police said.

According to testimony presented during a two-hour bench trial on March 19, Hertgen had previously attempted suicide inside the Mercer County Jail about a week after his arrest.

During the hearing, prosecutors relied on investigative reports, medical records and lab evidence, while Hertgen’s defense called forensic psychologist Dr. Gianni Pirelli, who testified extensively about Hertgen’s deteriorating mental health, NJ.com reported.

Pirelli described a documented history of escalating psychosis and schizophrenia marked by religious delusions, apocalyptic beliefs and what he called “prophetic and divine visions.”

Testimony detailed the onset of Hertgen’s schizophrenia in 2021 and his efforts to seek treatment, including a 2023 road trip to California for a treatment program, during which he kept a journal documenting his struggles.

On the day of his brother’s killing, Hertgen had reportedly gone grocery shopping with another brother before suffering what experts described as a severe psychiatric break.

Following the March hearing, Mercer County Superior Court Judge Robert Lytle ruled that Hertgen was legally insane at the time of his brother’s death and was not criminally responsible for the killing.

A custody hearing had been scheduled to decide Hertgen’s placement in New Jersey’s psychiatric hospital system.

The Hertgen brothers grew up in Toms River, New Jersey, where both were standout soccer players at Toms River North High School, according to NJ.com.

Joseph Hertgen later played soccer at the University of Michigan and worked as an analyst for a company in Red Bank. Matthew Hertgen graduated from Wesleyan University in 2015, where he also played collegiate soccer, before later working in finance as a telecom company vice president.

In his obituary, Hertgen’s family remembered him as a compassionate person whose life was overtaken by mental illness.

“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 says. “He departed with the love, friendship and forgiveness of his family and the eternal hope of salvation. May he rest in peace.”