Responding police officers found Patrick Maupai, 40, on the lawn of the New Milford Avenue home he shared with his mother, Linda Maupai, across the street from Dumont High School, shortly before midnight Sunday.
He was still on the phone talking with the dispatcher, the prosecutor said.
Maupai had admitted hitting his mother with the fire iron, Musella said. He also told the dispatcher that he believed she was dead.
Inside the house police found a gruesome scene on the living room floor, one that's better left undescribed.
They retrieved the fire poker, which was bent -- an indication of the force with which it had been swung, responders said.
Members of the Dumont Volunteer Ambulance Corps took Linda Maupai to Hackensack University Medical Center after trying to revive her with help from Holy Name Medical Center medics.
She was pronounced dead at the hospital at 12:50 a.m.
The single, unemployed Patrick Maupai was immediately seized, Musella said.
He remained under the guard of the Bergen County Sheriff's Office at Bergen New Bridge Medical Center in Paramus on Sunday, charged with knowing and purposeful murder and weapons offenses.
A first appearance was being scheduled in Central Judicial Processing Court in Hackensack.
Detectives from Musella's Major Crimes Unit are investigating along with Dumont police and the sheriff's Bureau of Criminal Identification, which collected the suspected murder weapon, among other evidence.
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