Poison tree mystery

One of New Zealand's poshest streets - home to Prime Minister John Key - is at the centre of a tree-poisoning mystery that cameras, a private detective and months of investigations have so far failed to crack.

Thirty-three mature and native trees were poisoned and killed around St Stephen's Ave and Pt Resolution Park in Parnell at the end of last year.

The leafy street - home to Key's $7.3 million mansion - has been the subject of extensive Auckland City Council inquiries to try to discover who planted the coloured poison at the base of the trees.

Documents released to the Herald on Sunday under the Official Information Act show the council has gone to extraordinary lengths to find the culprit, including hiring a private detective, and scouring hours of footage from CCTV cameras owned by local residents.

Equinox Group, the developer of the White Heron Point development, two apartment blocks under construction on the border of the Pt Resolution reserve, say they have been helping the council try to find the culprit. They have also laid a complaint of wilful damage with police.

The apartments have stunning views overlooking Auckland's waterfront - and even better views without the trees.

Council environmental officers tracked down a person who they believed to be responsible.

But during a telephone call to arrange a meeting, the line went dead, and the person has not been located since.

Concerns were first raised when mysterious purple, pink and beetroot-coloured dye starting appearing around the base of the mature trees in the Pt Resolution Reserve and around the apartment development on August 22 last year.

Council arboriculture adviser Simon Cook visited the site and took samples of the dye for testing. It turned out to be a herbicide called Tordon Brushkiller.

The trees then started showing signs of distress and began dying.

By September 11, when Cook revisited the site, the damage was clear. In an email that same day, Cook described to council colleagues how a number of trees - including karaka, karamu, pohutukawa, puriri and magnolia - had poison around their bases.

"The dye-coloured poison is very deliberately laid and now mature specimen trees have been killed, and more may well die," he said in the email.

"Trees that are dead are on private property and in the reserve; all impact upon the views of the new apartments being built."

Cook described the act as "blatant vandalism and very sad".

Meanwhile a private investigator was hired and the CCTV footage from private homes near the site was scoured.

High-profile buyers of the apartments include PGG Wrightson chief executive Craig Norgate, V8 racing guru Mark Petch and former Auckland mayor and breakfast cereal baron Dick Hubbard.

Early this year Cook interviewed the owner of one of the apartments.

That person told Cook that the culprit had left a trace of the coloured poison back to the apartment block, a move he thought was a deliberate attempt to try to pin the blame on the developers.

Travis Coffey, development manager of the White Heron apartments, said that Equinox "categorically deny any involvement whatsoever of the poisoning of the trees".

Coffey added that the company had spent a "substantial" amount of time helping the council investigations, including sending samples of the coloured dye off for testing.

"It's a disgrace that such a thing has happened and as well as that it is in our interest that we rejuvenate that park."

A possible breakthrough occurred in early February when Cook and a colleague went to an Auckland address to interview a person of interest to the inquiry.

There was no one home, but after leaving a card the person called back two days later.

In report about the incident Cook writes he discussed the issue with the person and was arranging a meeting at Pt Resolution.

"He seemed happy with this. We were arranging a time to meet when the telephone went dead."

Subsequent attempts to contact the person have since failed.

A search warrant was sought to search an unnamed Auckland property for any signs of the Tordon Brushkiller herbicide.

However, the application to search the property was declined by the court.