Police are considering sending officers to the US as part of the search for Nai Yin Xue.
Detective Inspector Dave Pearson said police are in contact with American authorities three times a day and the US agencies were following up on leads but he would not discuss their nature.
Herald reporter Patrick Gower - in Los Angeles - said Nai Yin Xue would have dissolved into the several blocks of Chinatown after touching down in the city on Saturday.
Mr Xue's picture is dotted across Chinatown, with the story running in all six of the Chinese language newspapers on display at the news kiosks.
The four street section of LA comprising Chinatown was the scene of the last sighting of Xue, where he got off a $20 airport shuttle bus.
Gower said there was no visible police presence in the area, made up of small restaurants, supermarkets and travel agents.
The area would have made a handy temporary stop-off point for Xue but the majority of China's Asian population lives in the Eastern suburbs of the city where Xue himself lived in 2000, he said.
Mr Pearson, speaking at Auckland Police Headquarters, this afternoon said more New Zealand police officers were being brought into the investigation, taking the number here to 25.
Sending some officers to the US to assist with inquiries there was also being considered.
Spokeswoman for Auckland police Noreen Hegarty said sending New Zealand officers over was being considered but no timeframe for a decision was known.
"We'll see how thing progress," she said.
As to where in the US they would be sent, Ms Hegarty said: "wherever needed".
He also revealed today that a US Government agency was searching for Mr Xue as early as Sunday night but he would not say which one or why.
Mr Pearson said calls were continuing to come in to the 0800 number with police following up on those inquiries.
He would not confirm the cause of Anan Liu's death, despite reports in American media that she was beaten to death.
"We have matters we have to put to the person responsible," Mr Pearson said.
Police have come under attack for their handling of the case, particularly the length of time it took to find the body of Xue's wife An An Liu in a car parked outside the family home.
They have defended the inquiry, but today Mr Pearson said investigators were possibly too cautious in complying with the rules.
"We obtained the car is relation to the abduction to the child, we had no other authority.
"The fact that she was missing was gaining importance. Yes, maybe we should have looked earlier," Mr Pearson said.
This afternoon Mr Pearson said he had full confidence in Detective Senior Sergeant Simon Scott who is heading up the investigation.
Earlier Mr Pearson said: "We were possibly too cautious in complying with all the regulations and rules and looking towards evidence for court. We were looking down the track in a year's time when we may be going to court over this.
"We were organising with ESR scientists and forensic people to look at that car."
Mr Pearson denied it was an oversight but says police could have looked at the vehicle sooner after seizing it.
The concession came after police staunchly defended their handling of the An An Liu homicide inquiry.
Deputy Police Commissioner Rob Pope commended the inquiry yesterday, saying it had proceeded "in keeping with best professional practice".
But he would not elaborate on details of the investigation, other than to say there were processes that had to be followed and ignoring them jeopardised evidence in a future court case.
Ms Liu's body was found in the boot of the car, 16 hours after the car was seized by police and 45 hours after police first visited the Mt Roskill street where the family lived.
Police became involved in the case on Monday, two days after Mr Xue abandoned their daughter Qian Xun in Melbourne, when Interpol asked them to door-knock four addresses, including Mr Xue's home in Keystone Ave.
By Tuesday morning the case was referred to the CIB after it was decided there could be some "sinister developments", police said.
Operation Patch was formed as a missing persons/possible homicide inquiry. The house was cordoned off with police tape that afternoon, but not the car.
A police search warrant for the car was granted at 9pm that night; it took two more hours before it was towed away. Police discovered the body at 1pm on Wednesday.
Mr Pope said all aspects of the inquiry had been performed properly and efficiently. Searching the car without a warrant may have tainted evidence that would have then been inadmissible.
"Until such a time police had determined that the vehicle was of some interest, it could not have been cordoned off, [or] secured, for forensic examination," he 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 it was not surprising the body was not discovered until 1pm the day after the car was seized, given the nature of gathering forensic evidence.
He would not say why police did not consider the car to be of interest at the same time that Mr Xue's house was cordoned off.
"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."
He said police had placed a notice with Interpol Washington by noon on Tuesday, but had no powers to direct them.
A former high-ranking police officer, who did not want to be named, said the delay in securing the car was inexcusable.
"It is not a crime for the police to take that car away and secure it because you know the owner has shot through from the country and there are suspicious circumstances here.
"Nobody is going to criticise you for doing that. I wouldn't have left the bloody thing there, unattended and able to be stolen or contaminated."
Police Commissioner Howard Broad told Newstalk ZB yesterday that police had not thought the car was of great significance.
He was disappointed it had taken so long to find the body.
- with NEWSTALK ZB