Princeton, New Jersey, the man accused of killing his brother and family cat is scheduled to appear in court for the first time Thursday.
Matthew Hertgen, 31 years old He was charged with first-degree murder In connection with the death of his 26-year-old brother, Joseph Hertgen. He is also charged with third and fourth degree weapons charges related to possession of a golf club and knife, and animal cruelty related to the death of a cat.
Hartgen is expected to effectively appear Thursday morning for a pre-trial pretrial detention hearing in Mercer County. With New Jersey's bail reform, criminal defendants will be charged with subpoena and allowed to return home until court date, or charged under a warrant, and held until pretrial detention hearing.
“In this case, the prosecutor's office will decide whether the Mercer County Prosecutor's Office will take you into custody or want to release you,” David Gelman, CEO of Germain Law and former New Jersey prosecutor, told Fox News Digital. “If you're in custody, you need a detention hearing that's going on tomorrow. And in the detention hearing, they're trying to raise evidence. It's almost like a mini trial.”
The Princeton man is said to have killed a former star athlete brother, cat before sharing a creepy poem on social media
Matthew Herdgen (Mercer County Prosecutor's Office)
Prosecutors can raise “possible causes statements” during the hearing, and may even call them “witnesses or two.” German explained.
There is also a scoring system for criminal defendants in New Jersey. That is, those accused of a crime are assigned a “score” of 1 to 5, depending on the nature of the suspected crime, with five representing the worst crime.
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Joseph “Joey” Hartgen signs with the University of Michigan as a soccer player. (Tom's River Regional School District)
Gelman also expects Hartgen's defense, currently listed as Jamie Hubert, a public defense counsel, will seek mental health tests. The Public Defender's office told Fox News Digital that the lawyer had not commented on the pending case.
“I feel there is some type of mental issue going on here. [in his 30s] And he has no criminal history at all… From what I understand, he is a pillar of the Toms River community where he grew up, a very wealthy area, and he currently lives in Princeton. It's very wealthy,” Germain said.
Princeton police initially answered a 911 call on February 22 at about 11:16pm, reporting a fire and body at the Michelle Muse Apartment complex. (University of Michigan | Wesleyan University | Google Maps)
Princeton Police first responded to a 911 call on February 22 at about 11:16pm Report fire and corpses In the Michelle Muse Apartment complex.
Upon arrival, police determined Matthew Hartgen was the caller of the 911, and at his residence, along with his brother's body, “showed signs of trauma and laceration of blunt force,” the Mercer County Prosecutor's Office said in a press release.
The Princeton man was accused of killing a former star athlete brother, a golf club cat and a knife near an Ivy League school
A general view of the Michelle Muse Housing Complex, located in Princeton, New Jersey, February 26, 2025. Matthew Hartgen is said to have murdered his brother Joseph inside his apartment on Saturday. (Kevin Downs from Fox News Digital)
Authorities have not yet explained any kind of motives related to Hertgen's murder charge. The suspect shared ominous graphic poems on his Facebook profile in September and May 2024.
Joseph Hertgen has been declared dead at the scene, and the results of his autopsy are pending. Local and state officials are investigating the death of the 26-year-old as a murder.
Joseph Hertgen was a soccer player at the University of Michigan. (Facebook)
Germain said the community was shocked by the murder.
“This is unusual and perhaps an understatement.”
“Princeton is a very wealthy area. … There's a house, minimal, you're probably looking at 750[,000] And it's probably like a small shed. So you're talking about some big money territory. And the police… want to make sure there's no crime, so it's very common there. It's a safe area. You have a lot of private schools… so you're talking about a very wealthy, wealthy area of Princeton. ”
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Both brothers played College Soccer: Matthew at Wesleyan University in Connecticut at College Soccer: University of Michigan at Joseph.
An investigation into Joseph's death is underway. Mercer County Authority Anyone with information about a suspected crime is asked to contact the Murder Task Force Sergeant. Jett at 609-331-5010 or det. Carl Johnson at 609-439-5258.
