Police could have prevented the death of a Hamilton woman who was bludgeoned with a hammer by her mentally ill neighbour, a report today reveals.

Diane White, 53, was killed in her Frankton home in January 2010 in a prolonged and frenzied attack by her former neighbour, Christine Judith Morris, 42.

Morris had earlier escaped from the Henry Rongomau Bennett Centre (HBC), a mental health facility at Waikato Hospital.

She was convicted of murder last April and was sentenced to life imprisonment with a minimum non-parole period of 10 years.

This morning a report released by the Independent Police Conduct Authority (IPCA) confirmed police had the information and the ability to have prevented White's death.

The report revealed the police communications centre received a 111 call from a HBC nurse about 11.30am after a concerned neighbour rang her to report that Morris was at White's house and making threats.

However, police didn't send any officers because they thought it was a repeat of information from an earlier call from the HBC nurse.

About 50 minutes after that call, the neighbour rang 111 to say Morris was leaving White's house with blood on her face.

Police were dispatched and found White dead.

The IPCA said that if police had been dispatched to apprehend Morris when the second call was placed it "was likely" White would be alive today.

Former Waikato police area commander Allan Boreham - who was in charge of the region at the time of White's death - today admitted police failed her.

Boreham, who is now assistant commissioner Upper North Island, said he had met with White's family and apologised on behalf of police.

"Police clearly failed Diane when she needed us after several individual errors came together on the day that resulted in a situation that had tragic consequences," he said.

"We are deeply sorry for what happened and I've met with her family in person to tell them this."

Boreham said responding to incidents involving people with mental health issues was often a very complex and challenging area for police officers.

"Notwithstanding that, the sequence of events that occurred in Hamilton that day are a tragic reminder that we have to be at our best at all times, even when dealing with what may initially appear to be routine matters."

Boreham said the police accepted all of the findings outlined in the IPCA's report, which echoed actions already undertaken following their own review of the incident.

"While we know that it will not bring Diane back, we want to make sure it does not happen again," he said.

"It is clear to me reading this report that if staff at the time had a greater focus on the threat to Diane, we could have done more to protect her and this tragedy could have been averted."

Changes brought in include a quality assurance process for communications centre staff, improved training, and technical upgrades to the centre's systems to provide automatic updates to dispatchers.

There was also a memorandum of understanding with the Ministry of Health that better defined responsibilities and processes to be followed when dealing with incidents involving mental health patients.

Police have upgraded its policy on people with mental impairments, which sets out steps for returning mental health patients who are reported missing.

- © Fairfax NZ News