Warning: This story contains graphic details

The man who stabbed four people during a frenzied knife attack in a central Dunedin supermarket will spend at least six years behind bars.

Luke James Lambert was this afternoon jailed for 13 years on each of four counts of attempted murder.

The 43-year-old will serve the sentences concurrently and his non-parole period of six-and-a-half years means he will not be eligible for release until late 2027.

Lambert's knife rampage on 10 May last year injured two Countdown staff and two members of the public. Three of them were critically injured and required life-saving surgery.

The frenzy only ended when other members of the public, Countdown staff and police officers, including one who was off-duty, restrained him.

The High Court at Dunedin today heard the attack had left the victims with long-lasting physical effects and pain.

One of the victims said they had suffered nerve damage as a result of being stabbed in the face.

The victim directed comments towards Lambert, who spent most of the sentencing staring at the floor but briefly met the victim's gaze.

"I don't feel anger toward you. I feel pity," the victim, who was granted name suppression, said.

"I just hope you get the help you need."

Jorge Fuenzalida, whose wife Vanessa Andrews was also stabbed in the attack, told the court he was only at the supermarket after having lunch in town with his wife.

"We don't usually shop there. We were nearly at the end of our shopping when I heard a chilling scream for help. It was a scream of terror," he said.

His training as a Corrections officer kicked in and he went towards the attacker to assist victims, but became one himself.

"I was pleading for my life. My arm was useless and I couldn't defend myself.

"I could see in your face that you wanted to kill me. You were on a mission that day to kill people."

But the worst part of the attack was not being able to protect his wife when she came to his aid, Fuenzalida said.

Andrews feared her husband would be killed during the attack.

"There was blood everywhere, there was blood pouring out like a fountain," she said.

"You looked like you were going to kill him.

"Then you turned on me and started stabbing me while I was trying to help Jorge."

She said she feared the day Lambert was released.

"Mr Lambert is a dangerous man and he needs to be off the streets for the safety of the public."

Justice Eaton praised the bravery of those who intervened and provided first-aid following the attack.

"But for the immediate actions, the immediate response of work colleagues and shoppers ... there is little doubt that life would have been lost," he said.

Justice Eaton said he had viewed the CCTV footage of the attack.

"The actions, as we see them on the CCTV footage, are remarkable actions of bravery."

Prosecutor Richard Smith said the attack was brief, lasting only about a minute and a half. But it was frenzied, extremely violent and only the bravery of those present prevented it from being fatal.

Just half an hour before the stabbings, Lambert told an associate "someone is going to get it".

Lambert was agitated and claimed to his associate he was refused medication from his doctor.

There was no evidence he had sought any such medication.

A summary of facts said the then-42-year-old picked up a packet of four kitchen knives from a shelf at Countdown Dunedin Central about 2.30pm on 10 May and slashed at a supermarket worker who had her back turned to him.

Countdown Dunedin Central after the attack. Photo: RNZ / Nate McKinnon

"The blades of the knives were 70mm in length," the summary of facts said.

"The defendant has walked into aisle seven, which is the pharmacy section of the supermarket. The defendant walked halfway down the aisle where he has placed his backpack on the floor. He removed two of the knives from the packaging.

"The defendant, armed with the two knives, walked over to victim one, who was working in the aisle stocking a shelf and had her back to defendant. He approached the victim from the left side turning her to face him and using his right hand slashed the victim from the left ear lobe to the chin.

"As the victim walked back the defendant pushed her and she fell to the floor. The defendant was on top of the victim stabbing her around the head area, causing further lacerations to the chin and left ear. While the victim attempted to defend herself, the defendant continued to stab at the victim's body, causing multiple wounds and injuries to her forearms and hands."

While carrying out the attack Lambert told the victim: "I'm going to kill you".

Another supermarket employee ran over to pull Lambert away from the victim and attempted to restrain him.

As a result, Lambert swung the knife at him, stabbing him multiple times including one wound which was so deep it struck the pelvis bone.

Fuenzalida and another staff member attempted to intervene.

Lambert broke free and then turned his attention to Fuenzalida and Andrews, stabbing them multiple times.

"An off-duty police officer approached the defendant and he turned and threatened the female officer with a knife but continued to try and attack [Fuenzalida] who was on the floor," the summary said.

"Members of the public, Countdown staff and another police officer have then restrained the defendant at the scene."

They then provided first aid to the four victims until an ambulance arrived.

Their efforts almost certainly saved lives.

Lambert had earlier in the day been shopping at the Countdown store, buying a pie and a soft drink before attempting to buy two cans of beer, which was declined due to a lack of money.

He left the supermarket shortly after 1pm and was later seen in the Octagon by an associate about 2pm.

"The associate described the defendant as 'agitated and pacing around'," the summary said.

"The defendant spoke to the associate and said the 'Doctor wouldn't give him any medication' and that 'someone is going to get it'.

"When the defendant was asked by the associate who was going to get it, he said 'don't worry'."

Police obtained Lambert's medical records after the attack, including a summary of his prescribed medication, and found no evidence he had any medication denied.

When interviewed by officers after the attack he declined to comment.

Lambert initially pleaded not guilty to the charges of attempted murder and intended to go to trial.

He reversed course in December last year and entered surprise guilty pleas on all counts following a mental health assessment which found he was fit to stand trial.

The court heard there was some evidence Lambert had carried out the attack hoping police would end his life.

He had lived an isolated existence for much of the decade before the attack with only his mother and his dogs providing meaningful company.

His mother died in 2018 and his dogs also died.

He turned to alcohol and drugs, and was homeless at the time of the attack.

While Lambert had previously appeared before the court, he had no convictions for violence at the time of the stabbings.

Police praise for those who responded

Superintendent Paul Basham Photo: RNZ / Nate McKinnon

Following the sentencing, Southern District Commander Superintendent Paul Basham paid tribute to those who intervened.

"I'd like to recognise the Countdown staff who first intervened and were the initial victims. Members of the public then came to assist, restraining the offender and providing aid and comfort to the injured," he said.

"They all went above and beyond in what was an extremely fast-moving situation."

Dunedin Central Police Station sits right next door to the supermarket and the first on-duty officers arrived within minutes of it occurring.

"I am extremely proud of the efforts of everyone who helped to de-escalate the situation and minimise any further harm," Basham said.

Countdown director of health and safety Kiri Hannifin said she was relieved the legal process was now behind them.

"We hope today's sentencing provides some comfort for our Dunedin team as they continue to work through the ongoing impact of what was an incredibly traumatic event for them. We will

continue to support them as they do this.

"We remain deeply grateful to the Dunedin police and to the local St John Ambulance service for their quick actions on the day of this horrible event, and for their ongoing support and care

since."