Tips reveal hidden dope farm

Indoor cannabis plantations kept warm with stolen electricity. Photo / Supplied

A series of anonymous letters led police to a million-dollar indoor cannabis operation run by a refugee who stole $26,000 worth of electricity to heat and light the houses in which he was growing the drug.

And it has emerged he was deported from Canada in 2005 after being charged with setting up a similar operation in Toronto.

Van Huy Bui, 34, was convicted last week on multiple charges of cultivating and selling cannabis, possession of methamphetamine and theft.

Canadian police assisted with the investigation, and Detective Sergeant Karl Sobotka of the Toronto major drug squad travelled to Auckland to give evidence during Bui's nine-day trial in the Auckland District Court.

Originally from Vietnam, Bui came to New Zealand as a refugee and was granted residency. He went to Toronto in 2004, and was deported after his arrest a year later.

Mr Sobotka met and dealt with Bui at that time.

In December 2008, police discovered he and associate Binh Van Le had converted houses into commercial-scale cannabis-growing sites with an annual harvest worth between $800,000 and $1 million.

The police summary of facts presented to the court revealed Bui was caught after anonymous handwritten letters were sent to the authorities, claiming knowledge of an illegal drug operation.

Police went to the Target Rd, Glenfield, address mentioned in the letter. It was about 300m from a primary school.

Bui and Le were at the house, which had "crude coverings" over all of the windows. Officers could smell cannabis and executed a search warrant under the Misuse of Drugs Act 1975.

The house had been "heavily modified" inside and was "noticeably devoid of routine furnishings", the summary of facts said.

"The unoccupied dwelling had sustained significant superficial and structural damage consistent with the installation and ongoing operation of the sophisticated cannabis-growing set-up.

"One bedroom contained 40 cannabis plants with an average height of 600mm, each in buckets growing under suspended artificial light sources."

Another 128 cannabis seedlings were in a second bedroom, in growing trays also placed under artificial light.

A further 61 plants, 70cm tall, were set up in the garage, and 11.1kg of dried cannabis was seized.

"The property was fitted with a massive array of transformer lights, fans, filters and irrigation equipment," the summary said.

Under the house was an arrangement of circuit breakers and timing devices connected to an unmetered power cable.

Police said the devices were used to avoid the high power costs associated with such an extensive growing operation.

Power companies usually investigated unusually high power use in residential areas, which could lead to discovery.

It was estimated that Bui had "unlawfully obtained" $11,000 worth of electricity belonging to Meridian Energy at the house.

Police contacted the owner of the Target Rd property and found that Le rented another house she owned, in Beach Rd, Browns Bay.

Officers found an almost identical growing operation at that address and described it as a "unique arrangement".

"The similarities between the two ... extended to identical brand chemicals, identical size and configuration of containers and the associated growing equipment," the summary of facts said.

They found 147 cannabis plants, 88 seedlings and 700g of dried leaf - and another device fitted to a power cable.

It was estimated that $15,000 worth of power had been stolen from Mercury Energy at the Browns Bay address.

Bui admitted to the police during a video interview that he owned the operation.