Dunedin's new CCTV cameras, officially switched on yesterday, have already proved their worth.
A previously unreported assault was uncovered while police were checking the system's software. Five teenagers have been charged as a result.
Other offences had also been picked up, including another assault. Police are investigating those incidents.
The $200,000 system was officially launched yesterday. Signs were installed in the Octagon informing the public the cameras are in place, meaning police can now use footage in court.
"From later on today, we will be able to use it for evidential purposes," Dunedin-Clutha area commander Inspector Dave Campbell said.
As well as monitoring people's activities, the cameras also link to software that can identify the number plates of "vehicles of interest" that drive through the area.
On a large video screen in the Dunedin Central Police Station watch-house, views of the entire Octagon are split into 14 units that can be monitored 24 hours a day by officers and sworn volunteers.
Another screen will show the images in the senior sergeant's office.
The images come from 13 high-resolution 5-megapixel fixed cameras, and one 16-megapixel camera that was "very large in terms of capacity", Insp Campbell said.
The idea to use CCTV to battle night-time disorder was first raised more than four years ago.
The decision to go ahead, and funding from the Dunedin City Council and charitable trusts, was finalised this year.
Insp Campbell said the Octagon was chosen for the cameras, as it was the area in Dunedin with the highest rate of assaults.
As well as having high clarity, the system allowed certain areas to be enlarged if there was an incident, while officers or volunteers could still keep an eye on the wider area, something that could not be done with the "tilt, pan and zoom" cameras in most other centres.
Automatic number-plate-recognition software allowed registration numbers of vehicles that were, for instance, stolen or owned by disqualified drivers to be entered into the system, and police notified if the vehicle was recognised.
Footage would be kept for a month before it was overwritten.
Insp Campbell said the assault uncovered had occurred near the Robbie Burns statue on Wednesday, and police were still looking for the victim.
Five Invercargill youths were caught after the incident, in which the victim was punched and kicked in the head.
While the footage could not be used in court, as the system was not officially in place, the youths were charged with assault.
In the future, footage would "most definitely" come in useful for prosecutions.
The cameras worked both day and night. Infrared lighting had been installed so police could view footage from darker areas.
Police officers would observe the images most of the time. However, at peak times, on Friday and Saturday nights from early evening until 4am, volunteers, from a group of more than 40, would assist.
Insp Campbell said he would like cameras installed in other areas of the city. That would require added capacity to the system's server, but was possible.
