John Banks says he is not surprised a police watchdog has cleared the police over their investigation into his electoral returns.
The Independent Police Conduct Authority (IPCA) today cleared police over their investigation into John Banks' electoral returns but says officers took a narrow approach to the case.
In April 2012, the police received complaints alleging Mr Banks had provided a false return in respect of donations to his 2010 Auckland mayoralty campaign.
The police decided not to prosecute.
The police watchdog launched its own inquiry after receiving five complaints about the police investigation.
It said it was satisfied, from its inquiry and from interviews, that there was no interference or pressure on the investigation team from the police executive or politically.
It said the police took a narrow view at times and should have fully analysed some of the evidence.
However, it said the police should not be criticised for this and had taken a reasonable approach.
Mr Banks said he had no concerns about the police investigation.
"The police inquiry was full and comprehensive, it was led by one of the best homicide detectives in New Zealand, it lasted nearly six months.
"I was interviewed twice for nearly four hours on tape and they decided there was no case to answer."
IPCA chairperson Sir David Carruthers said police concluded that they could not prove beyond reasonable doubt that at the time Mr Banks signed the return he did so knowing that the particular donations were falsely recorded as anonymous.
The IPCA completed its investigation in April 2015 but could not publicly release its report then due to ongoing legal action.
Last week, the Court of Appeal acquitted Mr Banks of filing false electoral returns and cancelled a planned retrial, which allowed the authority to make its decision public.