Ate His Eye; He Believed His Brother Had to Be Sacrificed to Save the World | Matthew Hertgen

What happens when someone is sick enough to know they need help—but not well enough to understand how dangerous their reality has become?

At around 11:15 p.m. on Saturday, February 22, 2025, 31-year-old Matthew Charles Hertgen called 911 from the second-floor apartment he shared with his younger brother in the Michelle Mews complex in Princeton, New Jersey. Matthew told the dispatcher there was “a fire and a dead body” inside the apartment, but when the dispatcher tried to get more information about what had happened, Matthew wouldn’t explain.

“I’m not gonna go into any more details right now.”

Officers with the Princeton Police Department were sent to the apartment, where Matthew met them at the front door. Once they went inside, they found his 26-year-old brother, Joseph Thomas Hertgen, lying dead on the dining room floor with obvious injuries to his head and body. They also found the family cat dead on an ottoman in the living room.

Matthew was still inside the apartment, and officers noticed cuts, scratches, and abrasions on his hands. They detained him and asked what had happened to his hands, and Matthew told them, “I went into a fit of madness… maybe like forty minutes ago.”

Before we get into exactly what police found inside that apartment and what investigators believed happened during those forty minutes, I want to tell you who Joseph was.

Joseph was born in Danbury, Connecticut, and grew up in Toms River, New Jersey. He was an athlete from a young age and became a standout soccer player at Toms River High School North, where he was a two-time team MVP and a two-time offensive player of the year. In 2015, he also earned New Jersey Central II All-State soccer honors before graduating in 2016.

His talent eventually took him to the University of Michigan, where he played midfielder for the men’s soccer team from 2016 through 2019. Even though he dealt with an injury during his college career, he also did extremely well academically, earning three Academic All-Big Ten honors and three University of Michigan Athletic Academic Achievement awards.

In 2020, Joseph graduated from Michigan’s Stephen M. Ross School of Business with a concentration in finance and accounting. He later started working in finance, and by 2023, he was an analyst on the Portfolio Management team for Locust Point Capital, an asset management company in Red Bank, New Jersey.

Outside of work, Joseph loved traveling, continued playing recreational sports, and enjoyed competitive games of chess and ping pong. His obituary described him by saying, “He was such a kind person, had a great love of life and his smile brightened every room.” It also said, “He played on many sports teams, loved traveling with his friends, and always enjoyed a good game of ping pong or chess.”

Joseph came from a family where athletics were a big part of life. His parents, Debra Hertgen and David Hertgen, raised three sons: David Jr., Matthew, and Joseph, and all three boys played soccer growing up.

Their father, David Sr., was also very successful professionally. He worked for decades in the telecommunications industry and served as president and chief financial officer of WiLine Networks, a Princeton-based telecommunications company with estimated annual revenue between $25 million and $100 million.

The family lived for years in Toms River, where they owned a home valued at around $1.1 million, before eventually relocating to Princeton. The Michelle Mews complex where Matthew and Joseph were living was near Princeton University, and units there were reportedly selling for as much as $2 million.

Despite the family’s financial success, the people who knew them seemed to focus more on how involved and supportive Debra and David were with their sons. Joseph Mahon, who coached the boys at Toms River North, described them as good people.

“The Hertgens are good people. His mom and dad are great. They treated me very well.”

He also said, “They were great to me and the boys, anything I would ask for them to do, they would do — on and off the field.”

Their oldest son, David Hertgen Jr., also played soccer and remained close to both of his younger brothers.

Matthew was born in Long Branch, New Jersey, and over the years he lived in several places, including New Fairfield, Connecticut; Toms River, New Jersey; Manhattan; and eventually Princeton. Like his brothers, he was a talented soccer player and played at Toms River North before going on to Wesleyan University in Connecticut.

Matthew played college soccer there in 2014 and graduated in 2015 with a Bachelor of Arts degree in microbiology and biochemistry. Even though his degree was in the sciences, he eventually moved into finance and became professionally successful, working for years as a vice president in a senior finance position for a telecommunications company.

In February 2017, however, he was arrested for drunk driving in South Jersey. That case resulted in a three-month suspension of his driver’s license and roughly $1,000 in fines.

Then, around 2021, while Matthew was living in New York City, his mental health began changing.

As Matthew’s mental health began getting worse, David became very aware of what his brother was experiencing.

He was eventually diagnosed with severe schizophrenia, and over the next several years, his condition became progressively worse. Matthew began experiencing serious visual disturbances along with religious and apocalyptic delusions, and eventually his psychosis became almost constant.

At different times, Matthew said that he believed he had multiple souls. He also believed he was, as HE said, God, Jesus, or the anti-Christ, and his visions became tied to ideas about religion, supernatural forces, and an approaching apocalypse.

Matthew apparently knew something was happening to him and tried to get help. In 2023, as his condition continued getting worse, he drove across the country to California in an attempt to enter a psychiatric treatment program. During the trip, he kept a detailed journal documenting the visual disturbances and other things he was experiencing.

By 2024, some of what Matthew was experiencing also began appearing publicly in things he posted online.

In March of that year, he posted a poem on Facebook that repeatedly referred to a spirit and sacrifice.

Part of it read, he said,

“Why does the moonlight once again burn my skin? Do you want me to burn everything down? Must I sacrifice everything to your altar? Is there not enough ashes already? Have I not spent enough time in the furnace? In your furnace? What is that I hear you saying? That there must be nothing left of me? But is that really you speaking? Or is it the spirit?”

Then, on September 24, 2024, Matthew posted another poem.

He wrote:

“What have you created? Why have you created it? Who are you trying to strangle?”

“I can see the knives sharpening. I can hear the arrows whizzing. I can feel my heart beating. But can he?”

Then the poem described someone alone in a room.

“Someone sits alone in that room. That room where the walls shake. He still has a pulse. Blood still flows through his veins. But something is wrapped around him, squeezing him, choking him, suffocating him. Tightly wound around his head, fastened deep in his throat. Blood oozes out of his eyes.”

The poem ended with the person convulsing before Matthew wrote, “He’s lost. He’s asleep. He’s dead.”

The day before Joseph died, Friday, February 21, 2025, Matthew posted another image to Facebook. This time it was a selfie of him holding a cat toy and staring directly into the camera. His expression was described as a vacant or “thousand-yard” stare.

The next day, investigators were left trying to figure out exactly what had happened inside the apartment before Matthew called 911.

Once investigators were able to fully process the apartment, they got a much clearer picture of just how violent the attack had been. Joseph was lying in a large pool of blood on the dining room floor and had suffered severe blunt-force trauma to the back of his head, along with a massive laceration across his chest and abdomen that was deep enough to expose his chest cavity. His right eye was also missing.

Near Joseph’s body, investigators recovered a bloody knife and a blood-stained golf club. On the dining room table, they found a plate and utensils smeared with blood along with a small cup containing what appeared to be blood.

The “fire” Matthew had mentioned during the 911 call turned out to be the family cat, which officers found dead on an ottoman in the living room. Investigators determined that the cat had been beaten, stabbed, and partially set on fire.

Because of the amount of evidence inside the home, several agencies became involved in the investigation, including the Mercer County Homicide Task Force, the Princeton Police Department, and the New Jersey State Police Crime Scene Unit. Investigators documented the blood patterns throughout the apartment, collected and swabbed the dinnerware from the dining table, preserved the knife and golf club, and gathered other physical evidence from the scene. The lead investigators included Mercer County Homicide Task Force Sgt. Will Jett and Detective Karl Johnston.

They also started talking to Matthew and Joseph’s family, including their older brother, David Jr., and that helped them begin putting together a timeline of the hours before Joseph died.

David told investigators that he had spent several hours with Matthew that Saturday because Matthew was having a particularly difficult day. He also told them that Matthew had been dealing with schizophrenia for years and had been experiencing what the family described as terrifying visions.

Investigators then looked at the brothers’ phones and found messages that helped narrow down exactly what was happening during Matthew and Joseph’s final hour together.

Then investigators uncovered something that helped put the pieces together. There was surveillance footage from inside the apartment, and it had caught part of the physical confrontation between Matthew and Joseph.

Using the crime-scene evidence, David’s account, the phone records, and the surveillance footage, investigators were eventually able to reconstruct what they believed happened on Saturday, February 22.

At around 4:30 that afternoon, David picked Matthew up and spent several hours with him. They went grocery shopping, and during that time, David could tell his brother was doing badly. Matthew was described as extremely distressed, despondent, and actively dealing with his “terrifying visions.”

David stayed with him for hours before eventually driving him back to the Michelle Mews apartment at around 10:00 p.m. He briefly went inside when he dropped Matthew off, and Joseph was there and alive.

After David left, he was still worried about Matthew’s state of mind, so at around 10:15 p.m., he texted Joseph and warned him that Matthew was struggling with his visions. He told Joseph to contact him if he needed help.

Joseph replied, “Will do,” and thanked him.

A few minutes later, at around 10:27 or 10:30 p.m., David also sent a message directly to Matthew. He invited him to go hiking the following day and told his brother to “hang in there.”

Matthew never responded.

Sometime between then and the 911 call at around 11:15 p.m., Matthew attacked Joseph.

According to investigators, Matthew used a kitchen knife and a golf club to attack his brother and surveillance footage showed Joseph tackling Matthew to the ground trying to defend himself.

Joseph was beaten and stabbed, and investigators determined that the family cat was also attacked during that same period before being set on fire in the living room.

Then, at around 11:15 p.m., Matthew called 911 and reported “a fire and a dead body.”

There was one more thing investigators had to explain. Joseph’s right eye was missing, and they couldn’t find it anywhere inside the apartment. Because of that, along with the bloody plate and utensils they found on the dining room table, police believed Matthew had eaten his brother’s eye.

Matthew was taken into custody that night and charged with first-degree murder, weapons offenses connected to the knife and golf club, and third-degree animal cruelty.

Just a few days later, on February 27, 2025, Matthew made his first court appearance by video from the Mercer County Jail before Mercer County Superior Court Judge Amber Gibbs. He was handcuffed and wearing protective suicide-prevention clothing, and he didn’t speak during the appearance.

Assistant Prosecutor Tim McCann asked the court for additional time while prosecutors continued collecting evidence.

“At this time, I’m requesting a three-day statutory adjournment. I’m still in the process of obtaining and providing discovery.”

Around a week after his arrest, Matthew attempted to hang himself inside his jail cell and was kept under heightened monitoring afterward.

Meanwhile, Joseph’s family was preparing to bury him. On March 1, 2025, his funeral was held at St. Luke Roman Catholic Church in Toms River.

Then, on March 6, Matthew returned to court and appeared in person before Judge Gibbs. He was handcuffed, wearing an orange jail jumpsuit, and represented by public defender Jason Charles Matey. Matthew spoke softly during the hearing and voluntarily agreed to remain in custody, waiving his right to a bond hearing.

As the case moved forward, the main legal issue became Matthew’s mental state at the time he killed Joseph.

Clinical and forensic psychologist Dr. Gianni Pirelli conducted an extensive review of Matthew’s records and interviewed him as part of the psychiatric evaluation. That included looking at the progression of his schizophrenia, his journal from the 2023 California trip, and the beliefs he had developed over the years.

Dr. Pirelli later testified, “I don’t say this lightly, and I certainly don’t want to make Matthew or his family feel bad, but I think it’s important for me to say that when I saw him, and based on my record review, he has one of the most severe mental illnesses that I’ve seen.”

He also described Matthew as “one of the most severe cases of mental illness that I’ve seen of someone who can still hold a conversation.”

According to Dr. Pirelli, Matthew’s ability to sit down and communicate didn’t mean he was experiencing reality in the same way everyone else was.

“Matthew is constantly psychotic. He indicates, just even anytime he closes his eyes, he’s seeing tremendous visions.”

As doctors looked more closely at Matthew’s beliefs leading up to Joseph’s death, they also learned how his apocalyptic delusions had become connected to something he had read in Swiss psychologist Carl Jung’s The Red Book. According to Britannica.com, The Red Book is a personal, illuminated manuscript written between 1914 and about 1930. It is a record of Carl Jung’s “confrontation with the unconscious”, documenting his inner journey through dreams, visions, fantasies, and induced hallucinations, accompanied by his own intricate color illustrations.

One chapter in the book was called “The Sacrificial Murder,” and according to Dr. Pirelli, when Matthew read it, “It kind of clicks for him and he puts two and two together.”

In Matthew’s mind, the ideas in the book became connected to the religious and apocalyptic visions he was already experiencing. He became convinced that the world was headed toward some type of spiritual catastrophe and that a real sacrifice was required to stop it.

Matthew eventually believed that killing Joseph was that sacrifice. According to the psychiatric findings, he thought Joseph’s death was necessary to prevent an apocalypse and, as he said, save his own soul from eternal damnation.

Dr. Pirelli said that Matthew wanted relief from what he was experiencing and was willing to refer to it as psychosis when talking with doctors, but he still believed the so-called spirit he thought had taken over his mind was real.

“He’s still trying to understand what all these thoughts or beliefs are. He’s willing to call it psychosis, kind of for our benefit to have the conversation, and he wants to be able to try to get help and some relief, but he believes that the [supposed] spirit that overtook him in 2021 is basically too powerful for any medications or mental health treatment.”

A little more than a year after Joseph’s death, on March 18, 2026, Matthew went before Mercer County Superior Court Judge Robert Lytle for a one-day bench trial. There was no jury, and the entire proceeding lasted only about two hours.

The case was prosecuted through the Mercer County Prosecutor’s Office under Prosecutor Janetta D. Marbrey and Deputy First Assistant Prosecutor Michael C. Borgos. The state relied on the investigative reports, medical records, laboratory testing, and other physical and forensic evidence to establish that Matthew was responsible for Joseph’s death and the killing of the family cat.

However, by the time the case reached trial, something unusual had happened. The prosecution’s own mental-health experts had reviewed Matthew’s condition and reached the same conclusion as the experts working with the defense: Matthew had been legally insane when he committed the crimes.

Remember in the beginning when I said that Matthew had tried to get help! He knew something was wrong and he was trying to do something about it. Obviously, knowing that you’re struggling doesn’t necessarily mean you understand how serious your condition has become, but he wasn’t completely ignoring what was happening to him either. That’s not a small feat for someone going through this, so I think we need to remember this action.

Under the original first-degree murder charge, Matthew could have faced 30 years to life in prison, but, after reviewing his psychiatric history, prosecutors agreed that the appropriate outcome was a verdict of not guilty by reason of insanity, which would place Matthew under court supervision in a secure psychiatric facility instead of sending him through the normal state prison system.

Matthew’s defense was led by Attorney Matey, and Dr. Pirelli was the only witness called during the bench trial. His testimony focused on just how severe Matthew’s schizophrenia had become and whether he could understand the nature or wrongfulness of what he was doing when he killed Joseph.

At the end of the hearing, Judge Lytle accepted the findings from the mental-health experts and found Matthew not guilty by reason of insanity.

In explaining his decision, Judge Lytle cited medical reports showing that Matthew “suffered from schizophrenia and was actively psychotic at the time he committed the offenses contained in the indictment.”

He also said, “According to the doctors, the defendant has a documented history of a progressive psychotic illness, beginning in at least 2021, possibly and most likely earlier.”

Judge Lytle explained that Matthew did not “experience his actions as ordinary homicide.” Instead, “Within his psychotic framework, he believed that he was engaged in, what he called, a spiritually necessary act to prevent an eternal damnation.”

So although the court found that Matthew had committed the acts, it also found that he wasn’t criminally responsible for them because of the severity of his mental illness at the time.

And I think what makes this case different from a lot of the insanity defenses we talk about is that there really wasn’t a fight between the prosecution and defense over Matthew’s mental condition. Even the prosecution’s own experts agreed with the defense. That tells you just how severe his illness had become.

And a not-guilty-by-reason-of-insanity verdict didn’t mean Matthew was going to be released. He remained in custody while the court worked out his permanent placement, with the expectation that he would eventually be transferred to a secure state psychiatric facility.

A custody and placement hearing was originally scheduled for May 1, 2026, but that hearing was postponed. Matthew remained at the Mercer County Correction Center in Hopewell Township, and another hearing was scheduled for May 29 to review his mental status and determine where he would be placed.

But Matthew never made it to that hearing.

On Friday, May 8, 2026, correctional officers found 32-year-old Matthew dead inside his jail cell at the Mercer County Correction Center. Authorities treated his death as an apparent suicide, although a final autopsy report was still pending according to the information available at the time.

At that point, Debra and David had lost two sons in a little more than a year and, after Matthew died, his family acknowledged both the person he had been earlier in his life and the severe mental illness that affected his final years.

His obituary said, “Growing up, Matthew is remembered as a caring and loving person. He was blessed with a large and extended family who he enjoyed spending time with.”

It continued, “During his later years, Matthew struggled with severe and profound mental health issues; yet he expressed sorrow, and remorse in many ways. He departed with the love, friendship and forgiveness of his family.”

Instead of asking people to send flowers in Matthew’s memory, the family requested donations to NAMI Mercer, an organization that works with people and families affected by serious mental illness.

Since you listened to this case, maybe you’d be interested in:

She Killed Her Children — But Was it Mental Health Illness or Murder? | The Lindsay Clancy Case
https://murderandlove.com/she-killed-her-children-but-was-it-mental-health-illness-or-murder-the-lindsay-clancy-case/

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