Man Who Killed His Brother And Cat Dies In Jail After Judge Rules He Was Legally Insane

A former college soccer player who killed his brother and a cat was found dead in jail. According to authorities, his death was an apparent suicide. He has also previously attempted to take his own life a week after getting arrested for his crimes.

Matthew Hertgen, 32, died at the Mercer County Jail on May 8. According to the Mercer County Prosecutor’s Office, the cause of death is pending an autopsy. However, initial reports have determined his death as an apparent suicide.

His death comes after a judge ruled last week that Hertgen was legally insane. The court ruled that he was not legally responsible for the death of his 26-year-old brother Joseph Hertgen.

According to NJ.com, he was scheduled for a custody hearing in May that would have determined his future behind bars. The charges against him stemmed from an incident on February 22, 2025.

Matthew was accused of using a knife and a golf club to attack his brother. Then, he allegedly ripped out and ate Joseph’s eyeball. According to the New York Post, detectives found a plate and other utensils smeared with blood inside his home. A cup was also found filled with blood.

In addition to facing a first-degree murder charge and weapon offenses, Hertgen was also charged with animal cruelty for killing a cat. The New Jersey native allegedly set a cat that lived in the area on fire.

During the investigation, Matthew and Joseph’s older brother, David Hertgen, said Matthew had been struggling with mental illness for the last five years. According to a probable cause affidavit, he had been “extremely distressed, despondent, and experiencing terrifying visions."

According to the affidavit, on the night of the murder, David informed Joseph that Matthew was having “visions” and asked him to help him if needed. Joseph responded, “Will do.”

Dr. Gianni Pirelli, a forensic psychologist who testified in Hertgen’s trial, said that he had a documented history of escalating psychotic episodes. “Anytime he closes his eyes, he's seeing tremendous vision,” the expert said.

Dr. Pirelli told the court that Matthew sometimes had “prophetic and divine visions,” which led him to see himself as a god or the anti-Christ. He believed that a “sacrificial murder” was needed to save the world. According to The Post, in February 2025, just a week after he was arrested, Matthew tried to kill himself.

In his obituary, his family further detailed his years of struggle with 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. He departed with the love, friendship, and forgiveness of his family and the eternal hope of salvation. May he rest in peace.”