The Princeton man charged with the beating death of his brother last weekend left a bloody scene and told arresting police officers he went into a “fit of madness,” a detective wrote in court papers.
Matthew Hertgen, 31, is charged with first-degree murder and related weapon possession charges in the death of Joseph Hertgen, 26.
The Mercer County Prosecutor’s Office has said the older Hertgen used a golf club and knife in the Feb. 22 crime.
A detective’s affidavit, publicized late Wednesday, described a gruesome scene when Princeton patrol officers arrived at the brothers’ apartment at 11:15 p.m. that night, in the Michelle Mews complex just off Witherspoon Street.
First, it was Matthew Hertgen who made the 911 call summoning officers, saying there was a dead body in the residence, which was his brother, and a small fire, the affidavit says. (Some parts of the affidavit were redacted.)
Matthew Hertgen said his brother had been dead for 30 to 40 minutes, according to the affidavit. Pressed by a dispatcher how Joseph Hertgen was injured, Matthew Hertgen replied: “I’m not gonna go into any more details right now.”
Police said Matthew Hertgen opened the door for them. Joseph Hertgen was on the floor of the dining room with significant injuries to his head, chest and upper body, police said. His right eye was missing, they said.
A bloody golf club was near the body, police said, and a pet cat was dead on an ottoman, partially burned.
Investigators also found what appeared to be a cup of blood, along with bloodied utensils and a plate, police said
As the officers detained Matthew Hertgen, they noticed his hands had cuts and scratches, the affidavit says. And when they asked how that happened, he said he “went into a fit of madness… maybe like forty minutes ago.”
Homicide detectives later spoke to another brother, who told them he’d spent the day with Matthew Hertgen and that he has struggled with mental illness for the past five years.
He’d spoke to his brother earlier in the day and went to be with him because he was depressed and despondent and experiencing “terrifying visions,” the affidavit says.
Wanting to help, the brother took Matthew Hertgen to a grocery store and another location, then back to the Princeton apartment at about 10 p.m. Joseph Hertgen was home by then, and the other brother informed him of what had occurred.
The brother later texted Joseph Hertgen and said to reach out if he needed any more help with Matthew Hertgen. “Will do,” Joseph replied, according to the affidavit.
The brother then texted Matthew Hertgen and said, “Hang in there.”
Matthew Hertgen did not respond.
When detectives tried to interview Matthew Hertgen and advised him of his rights, he sat in silence and said nothing to detectives, the affidavit says.
Hertgen is also charged with one count of animal cruelty. He is currently in the Mercer County jail awaiting a detention hearing in Mercer County Superior Court, scheduled for this week.
He was represented at a preliminary hearing by the state Public Defender’s Office.
The Hertgen brothers were standout soccer players at Toms River North High School, and each played in college. Joseph Hertgen played for University of Michigan, and Matthew Hertgen for Wesleyan University in Connecticut.
Joseph Hertgen graduated from Michigan and was working as an analyst for a firm in Red Bank.
“He played on many sports teams, loved traveling with his friends, and always enjoyed a good game of ping pong or chess. He was such a kind person, had a great love of life and his smile brightened every room,” his obituary says.
Stories by Kevin Shea
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Kevin Shea may be reached at kshea@njadvancemedia.com
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