Police Commissioner Howard Broad has admitted officers may have overlooked the significance of the car in which An An Liu's body was found.
Police this afternoon identified the body, found four days after An An Liu's husband - Nai Yin Xue - abandoned their daughter Qian Xun in Melbourne.
Mr Broad was this afternoon responding to criticism over the time it took investigators to discover Mrs Xue's body in the boot of the car parked outside the family's Mt Roskill home.
Mrs Xue, 27, died "during a violent episode", according to preliminary results from a post-mortem examination carried out this morning, police said. Mr Xue is now wanted for the murder of his wife and abduction of Qian Xun.
Speaking on Newstalk ZB, Mr Broad said officers made a judgement call not to open the car immediately, sealing it with stickers so that they would know if it had been tampered with.
"If we had thought that there was a person or a body in that car it would have been entered earlier but it was believed that it was a crime scene or a possibly a crime scene," he said.
"Had we entered the car without a search warrant we would have risked the evidence that was found - or could have been found - in that car having been tainted and not then admissible in court at a later stage.
"That was the thinking of the officers at the time. We can go back in hindsight and second guess and that's what we do and yes, it does look like it has been overlooked..."
Mr Broad admitted it was disappointing it took so long for police to discover the body but said it was easy to judge from a distance.
"You can sit there and look and say it would have been better to have access inside that car earlier - but look there are a million things going on at the start of these investigations...
"We follow a very steadfast process and I will go back over it and see what we can do better but it's very difficult to lay a judgement on the midst of all this on the officers who are well trained and doing things in the right way.
Deputy defends police
In Wellington, Deputy Police Commissioner Rob Pope also defended the police investigation, fronting a media scrum to "clear up perceptions around the police handling of the investigation".
"As is always the case, judgement calls have been made by the investigation team, and my assessment is this inquiry has proceeded in keeping with best professional practice," he said.
"We will, as a matter of course, fully debrief the investigation and if there are lessons to be learned, they will be fully taken on board."
Mr Pope addressed the issue of why it took so long to seize and then search the car; why Mr Xue was able to leave the country despite having a protection order against him and why it had taken Interpol so long start searching for Mr Xue.
"There are strict legal requirements around entry to vehicles in terms of admissibility of evidence in any court case. Unauthorised entry of a vehicle would mean that evidence could be regarded as tainted or potentially lost in the event of a prosecution case," Mr Pope said.
"If there had been any suggestion that a person was alive in the vehicle, then entry would have been made. Police have a responsibility and a regard to life, and that is paramount."
He said the search warrant for the car would have been applied for within hours of being granted at 9pm Tuesday.
It was not surprising that An An Liu's body was not discovered until 1pm the following day, he said.
He would not say why the car was not considered to be of interest when Mr Xue's house was cordoned off.
Formally identifying An An Liu's body this afternoon, Detective Senior Sergeant Simon Scott said police were now focusing on finding Nai Yin.
"Given all the circumstantial evidence to date - she was found in the boot of her husband's car outside their home, there was no activity on her bank accounts for at least a week before she was found, she'd had no 'phone or email contact with family and friends since Tuesday, September 11 - the homicide investigation team is focusing their efforts now on finding Nai Yin Xue, her husband," Mr Scott said.
Mr Xue left the country and abandoned his three-year-old daughter Qian at a Melbourne railway station on Saturday.
Mr Pope said there was no non-removal, issued by the Family Court, in place that would have alerted authorities and prevented him from leaving the country.
He said there was "nothing to suggest that any such order exists".
"Neither a parenting order, nor a protection order on their own, involves alert flags on either customs or immigration computers."
He said New Zealand Police placed a notice with Interpol Washington by noon on Tuesday.
"There are well-establish protocols that exist in terms of requests for international aid with enforcement agencies ... My advice is these have been followed.
"Contrary to some belief, New Zealand Police cannot directly request the assistance of individual policing agencies in other countries, nor can we direct that any particular inquiry should be made."
The Los Angeles Police Department has confirmed that it and other law enforcement agencies in the US can now legally search and detain Mr Xue.
Officer Jason Lee from the LAPD said Mr Xue if Mr Xue was found he would be detained and sent to the US Attorneys office for extradition to New Zealand.
This morning an Interpol official told Melbourne newspaper The Age a "red notice" had been sent from Interpol's Washington headquarters today informing the Los Angeles Police Department Mr Xue was "wanted urgently".
The FBI has been in contact with New Zealand Police but this evening a spokeswoman told nzherald.co.nz that it had not been officially requested to search for Mr Xue by New Zealand authorities.
LAPD officer Karen Smith earlier said it was possible Mr Xue could disappear into the large Asian community in LA.
A spokeswoman for Interpol in Washington had told nzherald.co.nz this morning that only the law enforcement agency seeking Mr Xue could comment on the case.
"We don't confirm or deny," she said.
- With NZPA, NEWSTALKZB, NZ HERALD STAFF