The officers were not hit but Henderson shot police dog Arnie at close range in the snout. It was a shot that downed Arnie immediately and caused him near-fatal injuries.
Judge Gene Tomlinson noted that if Henderson had simply gone to court on the charges for which he was wanted in the first place, the situation he created – one that could have ended with him facing a murder charge – would not have happened.
Police had a warrant to arrest Henderson and went to do so about 11am on December 1, 2020.
He had failed to appear in Dargaville District Court three and a half months earlier on charges of growing and possessing cannabis, unlawful possession of firearms and unlawful possession of the pistol.
Those charges arose after reports of Henderson firing a gun from a vehicle.
Police searched his house where they found a .308 calibre Ruger rifle lying beside a bed, a .22 calibre bolt action rifle that had been sawn off to become a 38-centimetre pistol, a 12-gauge shotgun, a .22 calibre rifle with five live rounds in it, two ammunition belts, multiple live rounds of 12-gauge ammunition, a 30-round magazine, and a glass methamphetamine pipe.
Also found was an indoor cannabis grow room, 13 cannabis plants, and 3kg of loose-leaf material.
Tomlinson said it was fortunate the officer in charge on the day of the incident in December made a decision – almost spur of the moment – to have his colleagues armed.
He said the decision saved police lives and likely saved Henderson from facing a life sentence in prison for murder.
Four uniformed officers, including the dog team, were involved in trying to arrest Henderson.
He ran across Tangowahine Valley Rd, jumped a wire fence and sprinted into a paddock.
Henderson ignored a warning to stop and that the dog would be released.
As the officers and dog ran toward Henderson, he crouched and pulled out a .357 Magnum pistol.
He then stood, holding the pistol with two hands and fired twice directly at the closest officer about 20m away.
The dog, Arnie, was shot just short of reaching Henderson.
The constable Henderson shot at was the dog handler who returned fire, injuring him in the stomach, hip, and right arm.
Henderson fell to the ground but was still clutching the pistol in his right hand. He only let go of it when the constable fired a further shot into the ground near him.
Henderson yelled, "You shot me, you shot me".
Judge Tomlinson asked Henderson what he expected would have happened after firing twice at police and hitting a police dog.
The police dog was flown by helicopter to Auckland and after numerous surgeries survived, although he was redeployed to a police search and rescue team.
In a victim statement for the court, the dog handler said he was scared Henderson was going to kill his friends that day.
He knew he had to shoot Henderson and save their lives and his.
Tomlinson said it was an extremely difficult decision for one human being to make, to consciously choose to have to shoot at another and the trauma that police officers face having been forced to open fire on someone else is something that he knew, from his experience, many officers never recovered from.
Henderson's actions ruined the officer's career – a job he was good at and loved.
Twenty-two years of his life came to a grinding halt that day, the officer said.
The gun Henderson used was later found to have been stolen in a burglary in Dunedin in 2016.
"In any other jurisdiction and with the possible exception of Great Britain, you would not have survived in any country such an encounter with law enforcement in these circumstances," Tomlinson told Henderson.
"I have no doubt that in any other country in the world you would not be here to deal with this ... you would be dead."
Henderson pleaded guilty to all charges after an earlier sentence indication. He was charged for the incident in the paddock with using a firearm against police, injuring a police dog, possession of a pistol, and possession of ammunition.
A later search of his phone led to him also being charged with an offer to supply cannabis and several counts of supplying and offering to supply methamphetamine – one involving an agreement to do so in exchange for a shotgun.
He was found to have supplied 35g of meth over 11 transactions, and five cannabis seedlings.
The judge rejected Henderson's suggestion he should get a sentence discount for being shot by police.
Henderson was issued a first strike warning.
He must serve 50 per cent of the sentence imposed before being considered for parole.
The judge also ordered forfeiture of about $5000 cash and destruction of the firearms and ammunition.
