One of the men responsible for the killing of a King Cobras gang member on a rural Canterbury road over an alleged drug debt has been jailed for more than 10 years.

Luke Sears, also known as Luke Riddell, was shot in the chest after a confrontation with Daniel Gary French and his associate Alistair Cochrane in October 2018.

French had been running a large-scale cannabis growing operation in the area, and Sears had bought cannabis from him.

The day before the killing Sears was "trying to collect" $40,000 he said French owed the King Cobras gang.

French believed Sears owed him $60,000 for cannabis he had purchased.

French and Sears met on Grange Rd, at Charing Cross west of Christchurch.

Both drove to the location - French with Cochrane and Sears with his fiancee.

A fight ensued and Cochrane then emerged from the car with a black shotgun.

Sears advanced toward Cochrane asking him: "what are you going to do with that?"

Cochrane said he was leaving, but Sears tried to take the keys from the vehicle and Cochrane pulled the trigger, shooting him in the chest and shoulder.

Cochrane and French drove off, leaving Sears dying by the roadside, with his fiancee desperately trying to get help.

French later returned to the scene, called police and claimed the firearm had gone off accidentally.

French and Cochrane were charged with murdering Sears and found guilty after a trial in the High Court at Christchurch.

However after an appeal, French had his conviction overturned.

A retrial had been scheduled for July this year but in June French pleaded guilty to a lesser charge of manslaughter.

He was sentenced this morning by Justice Rob Osborne.

French has already served about four years behind bars as part of his life sentence for murder.

Judge Osborne took that into consideration when handing down today's sentence for the new conviction.

He also heard a Victim Impact Statement from Sears' sister.

"Life without Luke has destroyed my family, we all used to be so close and this has ripped us apart," she told the court.

"Not only did you take his life, you took away my mum and part of her will to live. For every day there is a different walk of grief and a new struggle."

Sears' sister said she had "consistent nightmares" about the day he died.

"Nothing will ever take away the memory of the day; hearing my mum's gut-wrenching scream… to see her falling to the ground, the instant shock of what's happening and the disbelief that a human can take another human's life," she said.

She said she'd endured sleepless nights and struggled to get out of bed in the morning.

Her son, nieces and nephews also struggled with the loss of a male role model and father.

"His son grows up without a father, the struggle he has to go through is absolutely heartbreaking," she said.

"However long you will get [in jail] will never take away the pain and suffering you caused our family and it doesn't bring back Luke, it doesn't take away the depressing and the broken family."

French's lawyer Andrew Bailey acknowledged the victims and said it was clear that there were "significant consequences flowing from the death".

However, the court needed to also consider the victim's actions in the lead-up to the killing which he said were "causative".

That would "understandably invoke a reaction of unfairness" from Sears' loved ones but Bailey said the information was highly relevant.

He said in the days before he died Sears "carried out a number of brazen and unjustified acts of violence" and "extortion".

Luke Sears was killed on a rural Canterbury road in 2018. He was a member of the King Cobras gang, which has a distinctive patch. Photo / FILE

That included Sears threatening French and turning up at his "business" armed with a pistol he held to the man's head.

"These are events that the court simply cannot ignore," Bailey said.

"Mr Sears' actions were designed to induce fear into Mr French… if he didn't give him the money… it would cost him his life.

"There was every reason for Mr French to think Mr Sears was an imminent threat to his life."

Bailey said those fears were "well-founded and justified" and text messages between French and Sears proved that.

French begged Sears to "please, please" leave him alone.

"[French] was effectively being hunted by an extremely dangerous individual," said Bailey.

"There was a very clear causative link between Mr Sears' actions and death."

Bailey said despite those facts French never wanted to see Sears dead - in fact, he tried to get Cochrane to put the gun away.

Crown prosecutor Pip Currie said there should be no sympathy for French and there was no reason to "try to portion significant blame onto the victim".

"It seems to say 'poor Mr French, he found himself in a situation that was all of Mr Sears' own making'," she said.

"If we're wanting to examine the background we need to look at the fact that Mr French himself was heavily involved in the drug trade, with gang members… had access to firearms in the course of that.

"That was always going to be a dangerous situation for him to be involved in and as it turned out it was."

She said Sears was unarmed at the time he was shot and his death was "a huge and ongoing loss" to his family.

"It is clear that Mr Sears was a much-loved father, fiancee, son and brother… the trauma suffered by Mr Sears fiancee… is a cruelty which is beyond imagination," he said.

"I recognise that no sentence will redress the loss that you as a family have suffered."

Justice Osborne said French had engaged in a Restorative Justice meeting with one of Sears' sisters.

At that meeting, he said he would be "taking complete responsibility" in the context of the decisions he made "to become involved in the drug world".

Justice Osborne said there were a number of aggravating features in the killing.

They included the premeditation and taking a firearm to the meeting, the serious injury caused to Sears, the fact the victim was unarmed and the drug offending background.

There were also some mitigating features.

Two men have been jailed for the killing of gang member Luke Sears - one for murder and one for manslaughter. Photo / 123RF

Firstly, there was "provocation" by Sears, "particularly against his gang background".

"Your fears for your own safety stemmed from Mr Sears' own conduct... those fears were well founded," he said.

Justice Osborne said French "took genuine steps towards withdrawal" at the confrontation including telling Cochrane to put the gun away and trying to leave.

Returning to the scene and calling police also went in his favour.

However, the offending was still significant and serious.

Justice Osborne set a starting point of six years' jail but gave French a discount for his guilty plea and his "full and genuine participation" in Restorative Justice.

"I accept... that you have a genuine sadness about the outcome of your activities but that is not the same as remorse for your own involvement in Mr Sears' death," he said.

He gave a slight discount on the difficulties French would experience in prison due to the gang connection including not being able to access programmes and treatment the same as other inmates and possible delays to any parole.

Justice Osborne handed down a final sentence - including drug and other charges French was already convicted of - of 10 years and three months.

For the original murder charge, French had been sentenced to life with a minimum non-parole period of 10 years.

Under the current sentence French can apply for parole after serving a third of his time behind bars.