Two men found in a clandestine P-lab in an abandoned mine shaft on the outskirts of Whitianga on Saturday have been named.
Kerry Alexander Murphy, 40, and Grant Christopher Wyllie, 49, both from Whitianga, are believed to have died from carbon monoxide poisoning from a petrol-powered generator.
Police were alerted to the men's deaths by a female acquaintance of one of the men on Saturday. It is not clear if that person is facing charges.
Detective Sergeant Ross Patterson said the autopsy on the men's bodies found they died from carbon monoxide poisoning.
The operation was set up about 60 metres from the 309 Road, which is used by motorists travelling between Whitianga and Coromandel township, but was well hidden in the rough terrain on a steep hill in dense bush.
Mr Patterson said the operation appeared to be "relatively new". He would not reveal how much the methamphetamine operation could have produced.
"The inhalation of chemical fumes from the clandestine laboratory has not been discounted at this stage, and the cause of death will be determined by the coroner." Mr Patterson said police removed the bodies on Sunday.
They also recovered a "significant amount" of equipment and chemicals from near the scene.
He said those items had been confirmed as being consistent with a clandestine drug laboratory.
"There's been a lot of speculation about what happened.
"However, at this time I can confirm there was no explosion in or around the mine.
"This investigation is being treated as sudden deaths, as opposed to a homicide inquiry, and we're not looking for anyone else in connection to the deaths."
One person who lives near the place where the men were found said the road had a history of drug-related crime.
Mr Patterson said it was too early to comment on what substances were removed, as they still had to be analysed.
Officers spent 24 hours at the scene and specialists were required to carry out the difficult job of bringing the bodies of the men from the mine and down through the bush.
The bodies were removed at 3pm and several hours later eight police officers and forensic experts wearing protective gear appeared from the shaft. Firefighters were on alert for chemicals or flammable liquids when they were called to the scene about 9.30pm on Saturday.
The double tragedy showed the inherent risks to life of operating petrol-powered engines such as generators in confined spaces, Mr Patterson said.
People needed to realise that cooking controlled drugs posed a high risk to themselves and others around them, he said.
"In addition to that, in this case the question has to be asked where were the volatile waste materials associated with the manufacture of this drug are being dumped.
"These waste products are highly toxic and pose a risk, not just to people's health but to the environment as well."
Several people have been injured or killed when P-labs went wrong.
The first fatality was reported in 2007, when a 33-year-old man died from burns after a P-lab explosion at Te Hana, north of Wellsford.
Meth can be produced in between six and eight hours, hours using apparatus and cookware that can be dismantled rapidly.
Up to $10 million is spent annually on insurance claims relating to cleaning and sometimes replacing houses used to manufacture P.
More than half the clandestine meth labs police discover are in houses, garages or sheds in residential areas, but others have been found in caravans, vehicles, shipping containers, motels and baches.