Police were last night defending their investigation into a rampage that has cost four lives and left one hanging in the balance.

Mona Tuwhangai, 82, and Maurice O'Donnell, 72, were found dead in their home in the tiny coastal community of Kinohaku in the Waitomo district on Friday.

The body of Ross Bremner was also at the property; the 34-year-old had been on the run since the killing of his mother Clare, 60, and the stabbing of his father Keith, 64, who last night remained in an induced coma.

Police had been hunting Bremner since the Tuesday attack on his parents - after which they said there was "very low risk" to the public.

Neighbour of 12 years Ellyn Macpherson had earlier last week appealed for Bremner to give himself up.

But Bremner, a mental health patient who had been living in the community since 2013, travelled from his parents' home in Otorohanga - about 65km east - and is believed to be responsible for the deaths of the other couple.

Police said the bodies may have been there several days before they were discovered by a friend about 7pm on Friday.

They did not know why Bremner travelled to the house or whether he knew the couple.

Their bodies were removed in two hearses last night, after dozens of family members and friends, who gathered at the scene throughout the day, held a karakia.

One man performed an emotional haka and a police scene guard remained.

When Bremner's body was taken away in the afternoon, family members turned their backs to the hearse.

The Holden Vectra Bremner had driven to the home was taken away for examination.

Waikato Police acting district commander Naila Hassan said she was "absolutely confident" in the investigation and denied police didn't work fast enough.

Asked if she believed police could have done anything differently to prevent the three deaths, Hassan said police had attended to priorities in the right order.

Asked if police were ill-informed about Bremner's mental state as they told the public not to fear for their safety after the Otorohanga stabbing, Hassan said police had "gathered information" as they went through the investigation.

Hassan later released a statement explaining and defending the investigation.

She detailed the search area, number of properties checked, resources deployed and said other family had been taken to safe places.

"There was no information available to police to indicate where he would go," she said.

"This is a tragic outcome and we acknowledge the sense of shock this has brought to several close-knit Waikato communities."

Hassan said: "Our priority now is to establish the full timeline and circumstances of what has taken place.

"I know the community will be in a state of shock about what has occurred here."

Bremner's parents had just become grandparents for the first time. His mother had told friends her son had been in a dark place recently and his parents feared what he might do.

Police had said he had left with no cellphone, access to money and had few associates.