The pair fled to Hong Kong in early May after Westpac credited Mr Gao's account with a $10 million overdraft when he had asked for just $100,000.
Westpac has recovered most of the money but about $3.8m is still outstanding.
Two months ago Detective Senior Sergeant Tony Colby, of Rotorua police, said a "mutual-assistance" request to the Chinese government was being worked through.
That was still the case today and he admitted he did not know when there would be any progress, he told NZPA.
Mr Colby would not say if police knew where the pair were or if private investigators were looking for them.
"It's not a totally straight forward process and it has required a patient approach by the New Zealand authorities." The delay was not through any lack of co-operation from Chinese authorities, he said.
Mr Colby denied the delay was frustrating or embarrassing for police.
"Not really, we are used to working on complex inquiries that do require a considered, patient approach, and this is one of them.
"We are not embarrassed about it. We are doing our best and following all the appropriate steps. There's a process that has to be worked through and we have to have respect and regard for that.
"I think we would be embarrassed if we didn't comply with the proper process and tried to take short cuts." Police had a person in China speaking with the authorities there regularly, and were working with Crown Law.
Crown Law would not comment.
Westpac spokesman Craig Dowling would not criticise the police and neither would he be drawn on whether the case was embarrassing or frustrating for the bank.
"I think we have got a good working relationship with the police and are confident they are doing what they can."
If the police were successful with their inquiries the bank would work from there to recover the rest of the money.
Mr Dowling would not say if Westpac had taken other steps, other than through the police, to find the couple or the money.
"We can't really comment on specific measures the bank has taken at this stage."
However, Rotorua Sensible Sentencing Trust spokesman Peter Bentley said the case reflected poorly on New Zealand's foreign affairs capability.
"We haven't got the nous to have people in senior government positions to negotiate with senior Chinese with regard to extradition agreements.
"We haven't got one of those in place even though supposedly we have got free trade. What exactly are our parliamentary officials doing about it?"
