After treatment he was taken to Northland Region Corrections Facility at Ngāwhā, near Kaikohe.
However, Detective Inspector Rhys Johnston, of Northland Police, said officers were called to the prison on Monday morning after the man was found deceased.
Enquiries were underway into the circumstances of his death.
Both deaths had been referred to the Coroner and police would continue to investigate all circumstances, he said.
''Our thoughts are with all of the families involved,'' Johnston said.
The accused's name was suppressed when he appeared in court on Saturday.
Friday's murder has shaken the usually quiet harbourside town of Ōmāpere. Photo / supplied
Ōmāpere is a small, usually quiet harbourside town between Ōpononi and the entrance to Hokianga Harbour.
It is a popular tourist destination due to its scenic location, top-end accommodation, and proximity to Waipoua Forest and the dunes of North Hokianga Head.