The Privacy Commissioner will be investigating how a gang member was able to get the details of a police informant from a staff member at Vehicle Testing New Zealand.
Privacy Commissioner John Edwards said he was very concerned about the incident, which was mentioned by Justice Palmer in the High Court in Auckland yesterday as he sentenced six men for their parts in the fatal kidnapping of Jindarat Prutsiriporn.
The judge said police foiled an earlier kidnapping attempt by associates of the Head Hunters gang, known as the Ghost Unit, in February last year.
"At around 2.35am, the police arrived, having been called by a passer-by about the suspicious behaviour of a group of people. The group told the police they were waiting for their shift change in their security work and they dispersed.
"Disturbingly ... a captain in the Head Hunters was later able to obtain the name and address of the passer-by who called, through a source in Vehicle Testing New Zealand, from the licence plate of the car in which he passed by."
Mr Edwards said he would be asking VTNZ what happened and for an explanation of their security procedures.
The police have confirmed to RNZ that they have investigated the matter.
In a short written statement, Senior Sergeant Shaun Vickers said they spoke to all the parties involved and no charges were laid.
He said it was an internal matter for VTNZ and it would be inappropriate for police to comment further.
VTNZ general manager of operations Greg O'Connor said they fully investigated, and the employee no longer worked for VTNZ.
RNZ asked what assurances the New Zealand public could have that their details would not be passed on to gang members.
In a short written statement, Mr O'Connor said the integrity of VTNZ's system was vital and there were security protocols in place, but it was not possible to stop all breaches, especially where an employee went "out of their way to act fraudulently".
Seng Lek Liev was one of the six men jailed yesterday for their part in the kidnapping, which ended with Ms Prutsiriporn breaking her way out of a car boot and dying of head injuries after she hit the ground.
The court was told how the 50-year-old had been close to Liev - so close he had called her 'Mum' - but their relationship soured after they were both charged with possession of methamphetamine.
Angry text messages were exchanged and Liev eventually called on the help of two of his friends, Apichart Korhomklang and Sodarith Sao.
He also hired muscle in the form of the Ghost Unit to carry out the kidnapping.
The Ghost Unit was eventually successful. Ms Prutsiriporn was lured from her house on the pretence of a drug deal.
Two men threatened to shoot her and do harm to her family before bundling her into a car and driving her off.
She spent the next 19 hours bound and gagged in the boots of various cars and was moved around different addresses.
She was given no food or water.
At some point she found a chef's steel and a knife in the car boot.
Justice Palmer said it was out of fear that she used the steel to pop the boot open as the car was approaching traffic lights in the South Auckland suburb of Papatoetoe.
Still bound and gagged, she fell and hit the road surface. She died from her head injuries two days later in hospital.
Liev was jailed for 12 years and four months.
Sao and Korhomklang were jailed for 10 years, eight months and nine years, four months respectively.
Ghost Unit member Luigi Havea was jailed for 10 years and three months, Tafito Vaifale for seven years and 10 months, and Joseph Haurua for six-and-a-half years.