The officer who shot and killed a woman brandishing a hunting knife will have had a split second to react in a "frightening" scenario, a former top police negotiator says.
On Wednesday night, the Christchurch officer first shot and critically injured a man who was carrying a hunting knife and chasing his partner from their Bryndwr home.
They then shot and killed the woman when she picked up the knife and threatened officers.
Police figures showed 55 people had been shot dead by an officer between 1916 and the end of the last year - and just one of those who died was a woman.
Lance Burdett, who led negotiations with Jan Molenaar during the 2009 Napier siege, said officers were trained to use the most effective, least lethal method when they're threatened by someone with a weapon.
"But when you're in the heat of the moment like that, and particularly if they're in close proximity... you don't have time to get your weapon out, the necessary one that's available."
Officers had to make split second decisions to keep themselves and others safe, said Burdett.
They are trained to shoot at the "centre mass" because it's the largest part of the body - but unfortunately, that is where vital organs are, he said.
"I hear people saying 'why couldn't you shoot them in the leg?'. Well, you try, when somebody's running at you.
"This is not the movies, this is real life and it's frightening."
A hunting knife was a large, dangerous weapon that could do serious harm, Burdett said.
He said a Taser or pepper spray might work against a person with a knife but they required distance and time, which an officer didn't necessarily have in such a volatile and rapidly evolving situation.
"When people are highly emotional or on drugs or perhaps in some way mentally disaffected, these things don't work. Neither does communication... because they're not [using] the logic part of their brain they don't receive information the way it would normally be.
"People will be shouting and running around and there'll be a lot happening and you're expected to make a split second decision when things are really, really dynamic."
Police on Clyde Rd the day after they fatally shot a woman and critically wounded a man in Christchurch. Photo: RNZ / Nathan Mckinnon
Police and independent watchdog investigate
Police and the Independent Police Conduct Authority are both investigating.
The officer's decision to shoot would form a "large part" of the investigation, Canterbury District Commander Superintendent Tony Hill said.
Burdett said within a few days, that officer would be formally interviewed "like any other person" as part of a criminal investigation.
"You're given the Bill of Rights, you have the right to have a lawyer with you, and they will go through and interview exactly the same as any other person that's in that situation," he said.
The officer would also be supported by police and the union, Burdett said.
The Police Association President Chris Cahill declined to comment.
How events unfolded
Police were called to the Clyde Rd property in Bryndwr, Christchurch about 11pm on Wednesday after a person known to the couple called police to say the man was armed with a knife and threatening to hurt himself and his partner.
When officers arrived, the woman ran out of the house, followed by the man with a hunting knife.
"Police believed the woman was in risk of imminent serious harm, and fired a single shot, which hit the man," Commander Superintendent Hill said.
An officer approached the man to provide first aid, he said.
"The woman has picked up the knife and began to threaten officers, despite an appeal for her to put down the weapon, she has advanced on police, brandishing the knife.
"A second shot was fired, hitting the woman."
Officers immediately provided medical assistance, but she died at the scene, Hill said.
A nearby resident told RNZ the couple were "always fighting", while their church pastor said the community had been devastated by the incident.
The injured man was in a stable condition in Christchurch Hospital.
The police cordons at the scene were lifted on Thursday night.
Police at the site of a double shooting that resulted in one dead and one critically injured in Christchurch. Photo: RNZ / Sam Sherwood
Police minister's response
Police Minister Mark Mitchell says the officers involved in Wednesday night’s fatal shooting have his full support.
Mitchell called it “the worst case scenario for any police officer”.
Speaking to Chris Lynch Media, he said the incident was “an incredibly tragic situation” and that both the officers and the families of those involved were under immense strain.
“No police officer ever asks to be put in that position,” he said. “It is extremely stressful on them and their families, and support has been wrapped around them straight away. My condolences and thoughts go to the family and friends of the man currently receiving medical treatment, and of course, to those mourning the tragic loss of the woman who died. There are no winners in this situation, he told Chris Lynch Media.
Mitchell would not comment on the specific details of the Clyde Road shooting but said New Zealand police were “world-class” and received “world-class training” to deal with thousands of complex incidents every day. “We should be extremely proud of them,” he said.
Mitchell said the IPCA has “the resources, the independence, and the experience” to conduct a thorough investigation.
"They have been doing this for decades, they know how to handle these matters sensitively and properly."
Mitchell urged the public not to speculate on what took place.
"We should all wait for the findings of the investigation before making judgements,” he said.
"They (police) are doing an outstanding job making your communities safer. If you see a police officer, give them a friendly word of encouragement, because right now they will be feeling it."
