A prison sentence for a drug boss was cut by two years after he handed over an arsenal of illegal firearms to police.
Surrendering guns is a growing trend among underworld figures as a bargaining chip to reduce long prison sentences.
William James McFarlane, 47, was sentenced in the Auckland District Court this week after being found guilty in May of two charges of manufacturing methamphetamine.
On the eve of the hearing, McFarlane arranged for a cache of 15 weapons - including military style rifles and sawn-off shotguns - and ammunition to be given to police. In return, Crown prosecutor Scott McColgan suggested to Judge Roy Wade that MacFarlane deserved recognition for the act and a reduction in sentence.
Under normal circumstances the discovery of guns alongside drug manufacturing is considered an aggravating feature at sentencing, often resulting in longer jail terms.
But in his submissions to the court, Mr McColgan said a reduction in sentence for handing over the armoury was not inappropriate.
"Getting illegal firearms off the street, under any circumstances, can only be good."
Judge Wade agreed and cut McFarlane's sentence from 16 years to 14.
Detective Sergeant John Sowter oversaw Operation Royale, which arrested McFarlane and 12 others in August 2009, but no guns were found when police raided his home in the Tauranga suburb of Ohauiti.
He said McFarlane made the arms cache offer this week after arranging to meet the experienced drug squad officer in prison.
"The word on the street now is 'give the cops some guns and it will help with your sentence'," said Mr Sowter.
"I think it's a good deal. You don't like to see people getting reduction in sentence. But from a police point of view, those guns could be turned on the police or the community.
"Look at those sawn-off shotguns, those sorts of weapons are used in armed robberies. Getting them off the street is a bonus and should be encouraged."
The main target of Operation Royale was Christian Clifton, 48, who pleaded guilty to 10 methamphetamine manufacturing charges - each of which carries a maximum sentence of life imprisonment.
Bugged text messages and cellphone calls show Clifton was cooking methamphetamine in a clandestine lab in West Auckland and supplied the Class-A drug to a number of people including McFarlane, who bankrolled the P cook.
Over several months, McFarlane gave $120,000 to Clifton to help buy enough pseudoephedrine to make more than $1 million of methamphetamine.
Clifton, who has previously served a term of six years and 10 months for importing and manufacturing methamphetamine, is due to be sentenced next month.
McFarlane has also served four years and six months for manufacturing methamphetamine and was caught in Operation Royale soon after his release.
Drugs and guns
There is a strong link between the methamphetamine industry and illegal firearms, with an alarming number of high-powered weapons found when police investigate organised crime networks.
A black market exists in which a gun that a licensed firearms owner could legitimately buy for $3000 can be sold illegally for $12,000.
Police have no accurate idea of the total number of guns in the country, as records of firearms were abandoned in 1982 for a system of licensing owners.
However, a 1997 review by Sir Thomas Thorp suggested there was evidence of a substantial pool of weapons held for criminal purposes that could be between 10,000 and 25,000.