Mental health distress is a major factor in police shootings, a new study has found, often resulting in death.
Just under one in five incidents leading to an investigation by the Independent Conduct Authority between 1995 and 2019 involved mental health events.
Of those, 40 per cent resulted in police firing their guns. More than half ended in death.
Comparatively, police fired their guns in just 15 per cent of non-mental health-related incidents. A third of those incidents resulted in death.
The researchers say in 90 per cent of the incidents involving mental health events, whānau were aware of the person's current distress and/or history.
"These findings suggest opportunities to prevent the escalation of events to the point where they involve shootings," they said.
The researchers say the ethnicity of those involved wasn't clear as it's not included in the IPCA reports.
"Lack of ethnicity data limits the accountability of the IPCA and is an impediment to informed discussion of police response to people of different ethnicities, and Māori in particular, in New Zealand," the researchers say.
Of the shooting events, a "high proportion" involved people possessing a weapon, mostly either a knife or a firearm.
New Zealand Police's tactical options report last year found police are largely using force - such as Tasers, batons and police dogs - against Māori people.
More than half of incidents involved Māori people - more than the other ethnicities put together.
Police Association president Chris Cahill says the latest report highlights a key issue in New Zealand.
"We've got a mental health crisis and we've got a proliferation of firearms," he told Breakfast this morning.
"Police are at the forefront of both those issues and New Zealand has failed at both those issues. We need better mental health so these people aren't reaching crisis point with firearms in the first place.
"That would be the biggest issue to try and stop the risk to those people with mental health issues."
The analysis of IPCA reports was published in the International Journal of Law and Psychiatry yesterday.