Detectives have used an aerial drone in a criminal investigation leading to charges being laid and a person before the courts.
Police headquarters is refusing to say what type of inquiry it was or how the drone was used other than to describe the alleged offending as "criminal".
The case was one of two uses of drones by police last year which has led to the purchase of a helicopter-style drone to see how it would best fit with police work.
The emergence of the Unmanned Aerial Vehicle into law enforcement territory marks an advance on the controversial technology from conservation and mapping uses.
It also follows the revelation the air force's secret surveillance and electronic warfare plane is being used by police for tracking and monitoring offenders.
Writer and former press secretary David Beatson discovered the developing police interest through an Official Information Act request which showed the officers had already used drones on two occasions.
One occasion was in July last year when officers needed to photograph the area where Sofia Helen Athanassiou was found dead on Mt Victoria in Wellington. The steep bank, over-hanging trees and close scrub caused concerns potential evidence would be disturbed so a commercial drone operator was hired to fly over the area and take photographs.
Police told Mr Beatson there was one other case in which "an external company" had been contracted "to provide aerial imagery taken by a UAV to assist a police investigation".
Police headquarters refused to reveal further details other than saying it was a "criminal investigation".
The Kim Dotcom case was ruled out when suggested.
Mr Beatson was told police - with the support of the Defence Technology Agency - had previously had a drone demonstrated by a private company specialising in high-resolution images and 3D pictures which could be used for mapping. Officers were also told UAVs could provide video footage and infra-red images for night use.
"Police considered these products would be able to assist police in a number of ways," Mr Beatson was told. The technology had the potential to save lives during an emergency.
The trial led to police buying a drone to "evaluate its capabilities" - telling the Weekend Herald it was a helicopter-style drone which cost under $5000.
Privacy Commissioner Marie Shroff said drones were becoming cheaper and easier to buy and could be used to the benefit of society for research, planning and construction.
"But drones do have the potential to be seriously intrusive for people."
She said organisations using drones needed good privacy policies - or possibly a warrant.
"Organisations using drone technology would have to have a very good reason for collecting personal information in that way, and have very stringent controls on how the images were used and who they were disclosed to.
"We'd expect those organisations to think through the privacy implications and then consult with us about their proposals. It's possible to use drones lawfully, but only if you have good privacy policies and safeguards or other authority such as a warrant."
She said there were legal constraints on what drones could be used for - "it's not a free-for-all situation."