Two years ago North Shore closed circuit cameras spotted a man stalking his estranged wife.

Just 48 hours later he murdered her, Northern Busway stations team leader Anthony Blom says.

In the court sequel, former high-profile detective David McSweeney of Silverdale was sentenced to life imprisonment with a minimum non-parole period of 15 years.

It was revealed that he had been violent towards his wife Suzanne over a long period.

She had left him a few weeks before and he had been served with a protection order.

McSweeney was filmed sitting in his car at the Constellation Drive bus station watching her and a man.

Mr Blom says the news of the murder shook the worker who dealt with the tape.

The person wished the camera could have read the stalker’s mind and prevented the crime, he says.

Mr Blom and colleague Antony Vallyon say they have witnessed other criminal and indecent behaviour on CCTV.

Footage of two vandals who smashed 32 glass panels at the Sunnynook bus station, causing $25,000 worth of damage, led to the arrest of two men after the pictures were published in the North Shore Times.

Mr Blom and Mr Vallyon have been working with police and the Privacy Commission to come up with a policy for how CCTV is used.

Council CCTV cameras can only be placed on council land.

Community boards will be considering the issue over the next few weeks and public submissions close on May 23.

At last count there were 550 CCTV cameras on the North Shore, with 240 council-owned. Of those, 105 are on the busway.

They are generally put in areas that are crime hotspots.

Set up in carparks, bus stations and ferry terminals, the cameras are not allowed to show private property.

"The policy is to make sure we are using the technology in a responsible manner, to stop or deter crime," says Mr Blom.

"We have to justify putting the cameras in."

Mr Blom says the cameras are hugely effective.

"Often it’s a core group of people who are doing a number of illegal things and they eventually get caught by the police for something or other."