Princeton man charged with murdering brother at the Michelle Mews Apartments on Palmer Square

A Princeton Borough man allegedly murdered his younger brother Saturday night at the Michelle Mews Apartments on Palmer Square.

Matthew Hertgen, 31, has been charged with first-degree murder in the death of his younger brother, Princeton resident Joseph Hertgen, 26.

According to the Mercer County Prosecutor’s Office, Matthew Hertgen allegedly purposely caused the death of his younger brother and a cat that was in the apartment on Saturday night, Feb. 22.

Just after 11 p.m. Saturday, officers for the Princeton Police Department responded to a 9-1-1 call reporting that there was a fire and a dead body on the 600 block of the Michelle Mews Apartment units, which are part of the Residences at Palmer Square.

When officers arrived on the scene, they found Mathew Hertgen, who was the 9-1-1 caller, in the home along with the body of the victim, his younger brother Joseph Hertgen, whose body had various visible injuries including lacerations and signs of blunt force trauma.

Joseph Hertgen was pronounced dead at the scene.

A golf club and knife appear to have been used, according to the charges by the Mercer County Prosecutor’s Office.

Joseph Hertgen was an analyst for Locust Point Capital in New York City. A 2020 graduate of The University of Michigan, he was a three-time Academic All-Big Ten soccer player for the U of M men’s soccer team. Born in Danbury, Conn., he attended Toms River North High School and was a New Jersey Central II All-State soccer player in 2015. His brother Mattew Hertgen played soccer at Wesleyan University.

An investigation by the Mercer County Homicide Task Force, the Princeton Police Department and the State Police Crime Scene Unit led to the charges against Hertgen.

The exact cause and manner of Joseph Hertgen’s death will be disclosed after an autopsy has been conducted, law enforcement officials said.

First-degree murder carries a sentence of thirty years to life in state prison and a fine of up to $200,000. Third-degree crimes carry a sentence of three to five years in state prison and a fine of up to $15,000. Fourth-degree crimes carry a sentence of eighteen months to three years in state prison and a fine of $10,000.

In addition to the first-degree murder charge, Matthew Hertgen has also been charged with various third and fourth-degree weapons offenses for possessing a knife and a golf club, as well as one count of third-degree animal cruelty for the death of the cat that was in the apartment.

The investigation is ongoing. Anyone with information about the death should contact the Mercer County Prosecutor Homicide Task Force Sgt. Will Jett at (609) 331-5010 or Detective Karl Johnston at (609) 439-5248.