Former top policeman Clint Rickards exhibited bias and overstated some issues "to the point of exaggeration" in his complaints about Operation Austin, the Independent Police Conduct Authority has found.
The police operation Mr Rickards condemned as a shambles has been hailed by the judge heading the inquiry as exemplary.
IPCA chairwoman Justice Lowell Goddard yesterday said criticisms the inquiry was biased and had taken too long were unfounded.
In rejecting 15 separate complaints about Operation Austin from Mr Rickards and one from former All Black Steve McDowell, Justice Goddard painted a picture of Operation Austin which contrasted starkly with Mr Rickards' claim last year that it was a "shambles".
"There are aspects of it [the investigation] I consider to be exemplary and should be put into the police manual of best practice for the future."
There was "no evidence at all" to support Mr Rickards' statement that Operation Austin had been a shambles, Justice Goddard said. "In fact, the opposite."
The IPCA's response to specific complaints made by Mr Rickards and Mr McDowell were reported to them confidentially.
The IPCA can choose to publicly report on an issue of widespread interest, which was the step Justice Goddard took yesterday.
The report said there was a particular thread which ran through many of Mr Rickards' complaints. He tended to be "over-selective" in much of the material placed before the IPCA and a tendency to overstate some issues "to the point of exaggeration" was also noted.
"It appeared to the Authority that whilst the Assistant Commissioner has accused others of bias, he has on occasions engaged in precisely the same behaviour."
Justice Goddard emphatically said there was no evidence of bias or pre-determination in Operation Austin.
"Any investigation should be approached with an open mind and all of the evidence carefully weighed without any pre-determination or bias, and I am able to find quite categorically no evidence of bias or pre-determination in the Operation Austin investigation."
Justice Goddard said the decision to prosecute Mr Rickards and former colleagues Brad Shipton and Bob Schollum on charges which arose from Operation Austin was made after a thorough, independent and objective analysis of all available evidence by Christchurch Crown Solicitor Brent Stanaway.
Yesterday's IPCA's findings came as a rare bright moment for police in what has been a deeply embarrassing episode for the force.
Deputy Commissioner Rob Pope said he was delighted the complaints had been rejected, and that the investigation team had received high praise from Justice Goddard.
"The Austin team is made up of a group of people who have had this investigation as the focus of their professional lives for four years," Mr Pope said.
"It comes as no surprise that their integrity, skills and unflagging commitment throughout that time, particularly to the complainants involved, has resulted in such high commendation."