"Our role is to put the best evidence available before the court. We believe we did that," said Commissioner Peter Marshall.
"We will be taking the advice of crown counsel on any further representations to the court."
Mr Marshall said police needed to act on the information that was gathered before October 2007 and he will continue to support staff.
Prosecutor Ross Burns said the Crown would consider a retrial on the lead charge of belonging to an organised criminal group, on which the jurors could not reach a decision.
"Ordinarily, the Crown would proceed to a retrial, but it will have to consider it carefully in this case."
Auckland University law professor Scott Optican, who specialises in evidence and criminal procedure, said there were lots of important factors the Crown would have to consider when deciding whether to retry the four.
The most important was whether they believed they had enough evidence that would allow a newly constituted jury to convict the defendants beyond reasonable doubt - and whether they could reach a verdict at all a second time around.
"Obviously, when they went for the first trial they felt they had a prima facie case," Mr Optican said.
"They have to decide whether they still think that now. Do they have enough of a case to go forward a second time with a differently constituted jury?"
Mr Optican said public interest was equally important.
"Is it in the interest of the public to retry? Is it worth the time and the money?"
He said the Crown also needed to consider the perception of seriousness and the likely punishment that would be handed out and balance that with the resources required for a second trial.
He expected that decision to be made very soon.
"There's no real timeframe. They will announce if they will bring the charges again reasonably soon, I think. They'll make a reasonably quick decision and you can see why they would.
"Why would they want to drag it out? Obviously they are going to have to make a decision and that may have already happened."
Mr Optican said the verdicts had been a long time coming and the Crown needed to consider their next move very carefully.
"They did get the defendants on some of the charges.
"From their perspective, they got half of their case. Now, they must decide if they are satisfied with that. We'll just have to wait and see."