A new marking device that invisibly codes property could see burglars caught blue-handed.

A six-month trial of SelectaDNA - a synthetic DNA solution that glows blue under ultra-violet light - was launched in the Manukau suburb of Randwick Park yesterday.

New Zealand is the third country in the world to trial the product that marks property with a coded microdot, which is then matched against a database of registered owners. The solution can also be used in a hydra-spray form - at the entrance of a business - to help place offenders at the scene.

Yesterday police started knocking at 1000 Randwick Park doors to offer free domestic kits, each containing a bottle of solution, a small UV torch and a set of warning stickers saying "You Steal, You're Marked!" to be plastered on property and around the house. The trial was funded by SelectaDNA, Manukau City Council and Victim Support.

The marker is painted on like glue and marks property indefinitely, clothes for up to six months and skin for one to two weeks.

If successful in Randwick Park, it will be rolled out around the country.

BNZ banks in Counties-Manukau have installed hydra-sprayers at their doors - to douse robbers as they flee. Some branches in Papakura, Manurewa and Manukau already sell the domestic kits, at $100 each. They will be sold nationwide mid-October.

It may also be used by second-hand dealers and pawn shops to ensure goods aren't stolen.

The trial will mimic those carried out in Britain and the Netherlands, which produced a reduction in burglaries of uup to 55 per cent.

SelectaDNA director David Morrissey said the solution was introduced in the London suburb of East Dulwich last October.

He said it was triply effective.

"Firstly, it acts as a deterrent, but then if a person is caught they admit guilt at the first opportunity because the evidence is irrefutable," he said. "And if it goes to trial it has a 100 per cent conviction rate."

Mr Morrissey said the microdot link was a simple way of identifying the property.

"You take the number from the microdot, go on to the database and get the registered owner."

If a microdot could not be found, police could take a scraping of the solution and have it tested by ESR, he said.

Counties Manukau district commander Superintendent Mike Bush said there had been a number of anti-theft initiatives in the area, but was hopeful this was the winner.

"It is a real example of community policing. Working with our community we have identified what really matters to them."
* The worst districts

(Burglaries per 10,000 population):

Auckland City 212.2

Counties Manukau 178.2

Eastern (East Cape to southern Hawkes Bay) 171.8

Waikato 149.9

* How it works

Police find a suspected stolen item.

UV torch is used to look for a microdot.

If sufficient grounds to suspect an item is stolen, it is taken back to station.

Microdot code checked in the database and traced to the registered owner.

If a microdot is not located, a scraping can be taken and tested by ESR