Two police officers who detained a 17-year-old boy in an attempt to end a young love affair did so unlawfully, the Independent Police Conduct Authority has found.
The IPCA's investigation also uncovered documents showing one of those involved, Inspector Hurimoana Dennis, broke the law in a separate incident by using his powers to influence a prosecution against his own son.
Dennis and Sergeant Vaughan Perry were charged in 2016 with kidnapping a 17-year-old boy who was dating a 15-year-old girl against his family's wishes.
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In May 2015 the boy was detained at the Auckland Central police station, despite him not having been arrested or charged with any crime. Dennis and members of the boy's family pressured the teen to end his relationship with his girlfriend, who was 15, and go to Australia.
When he flew back in June he was detained at Auckland International Airport and put on a flight back to Australia.
At a High Court jury trial both Dennis and Perry were found not guilty of a combined three counts of kidnapping the teenager in relation to the two incidents.
But an IPCA report, released today, said it had found "on the balance of probabilities" that Dennis and Perry "unlawfully detained" the boy on both occasions.
The report said "Inspector Dennis' actions in attempting to force [the boy] to comply with his family's wishes were an abuse of his influence, power and authority as a police inspector".
He had also failed to address a conflict of interest arising from his relationship with the boy's family.
A senior airport-based officer had also directed other officers to unlawfully detain the teenager, the report found.
Several officers involved in detaining the teenager under orders from a superior were also criticised by the IPCA, which said they should have questioned Dennis' actions.
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The report also slammed NZ Police for a "flawed" employment investigation process which "lacked transparency, leadership and coordination".
"Nobody had oversight of all the outcomes to ensure they were consistent and appropriate."
The IPCA said police should have conducted an employment investigation into Dennis' actions concurrent with the criminal investigation process.
Police had also failed to property look into the actions of all the officers involved in the unlawful detention. Only one officer had been appropriately disciplined, the report said, with the disciplinary actions later downgraded to match the leniency with which other officers had been treated.
In a second report related to a separate incident, the IPCA also found Dennis and another staff member guilty of misconduct because they had influenced the outcome of a police prosecution of offending committed by Dennis' son.
Dennis retired from the police force in 2017 after more than 30 years on the job, latterly spent as the national Māori strategic advisor.
NZ Police respond to IPCA reports: Investigation was "thorough and robust"
Police said in a statement there were "learnings" to be taken from both reports in regard to employment investigation processes.
But they had carried out a "thorough and robust investigation" into the detention of the teenager and had examined all evidence in close detail.
"With the careful application of the Solicitor General's guidelines and independent legal advice, two officers were subsequently prosecuted and found not guilty by a jury.
"A number of our staff were the subject of employment processes in relation to this matter. While the details of these are confidential Police can confirm that Sergeant Vaughan Perry is working on full duties. Hurimoana Dennis has retired from New Zealand Police."
The fact Dennis and Perry had gone to court "shows how we hold ourselves to account and the expectations we have of our staff to act in line with our values and the high standards of behaviour expected by our communities", acting Deputy Commissioner Andy Coster said in the statement.
Dennis had retired before an employment investigation could be carried out into the reported misconduct.
The public rightly expected high standards from police staff, Coster said. The misconduct in the IPCA's report "goes against everything we stand for".
"We expect all staff to model our police values of professionalism, respect, integrity, commitment to Māori and the treaty, empathy and valuing diversity, through all parts of their personal and professional lives."