Key Points:

A cry of "hang yourselves" rang from the public gallery of an Auckland courtroom yesterday as prison sentences were handed down to the killers of 3-year-old Ngatikaura Ngati.

The toddler's mother, Maine Ngati, 32, and her partner, Teusila Fa'asisila, 27, each received prison terms of 8 1/2 years for the killing after being convicted at trial last month on charges of manslaughter, failing to provide the necessaries of life and child cruelty.

The couple were charged after Ngatikaura died in Middlemore Hospital within hours of receiving repeated beatings on January 30 and 31 last year.

His death came three months after he was returned to his birth mother. Ngatikaura's caregiver alleged in the Weekend Herald a month ago that Maine Ngati wanted the child back so she could claim more money in welfare allowances.

The beatings - administered with several weapons, including a baseball bat - were sparked by incidents such as the youngster soiling his pants.

The prisoners were ordered to serve a minimum four years and eight months each.

Yesterday's outburst in the High Court at Auckland came from a grieving family member sharing the public gallery with other relatives, who were wearing T-shirts printed with an image of Ngatikaura.

The officer in charge of the case, Inspector Richard Middleton, was left to restore order in the court, asking family members to "show some dignity for Ngati, all of you".

Kura Kaufusi - Maine Ngati's cousin and carer of Ngatikaura for the first three years of his life - said she did not think the sentence was long enough. However, she was unsure how long it should have been, just saying, "Longer than that."

She planned to take flowers to Ngatikaura's grave last night.

Ms Kaufusi said the case had created a rift between family members and she was glad it was over.

Mr Middleton said the case was difficult for police, family and court staff because of the violent nature of the crime on a young child. He said he was "really pleased it's finally over".

Children's Commissioner Cindy Kiro said the couple got what they deserved for an act of cowardice and ignorance. She hoped the sentence would serve as a deterrent to others.

Dr Kiro said people who knew violence was going on in families should also take notice because they were condoning the behaviour by not reporting it.

In his sentencing, Justice Graham Lang told the pair their household was otherwise normal, except when it came to discipline.

"You simply thought it was acceptable to strike them [children] and that was a usual way of dealing with situations that required discipline."

Each of them had a part to play in the series of beatings of a "defenceless" and "vulnerable" boy and in not seeking treatment until he was slipping in and out of consciousness.

"He was robbed of his life before it had even properly begun. That boy must have been in excruciating pain by the time he finally lapsed into unconsciousness."

Justice Lang said some family members knew of the abuse and if there was one positive thing that could come from Ngatikaura's death, it should be that family members would report abuse to the authorities.

Justice Lang told Ngati she had accepted responsibility from the beginning, was remorseful and "highly unlikely" to reoffend.

He told Fa'asisila that he accepted his remorse and his good work record as a security officer.

However, aggravating factors were the fact they beat Ngatikaura knowing he was already injured and used weapons on him.

Fa'asisila sat in the dock with his arms folded and Ngati fidgeted with her fingers until just before sentencing, when she cried.

Aucklander Kim Ace, who said she attended the case because she felt so bad for Ngatikaura, called for murder charges to be changed.

"I think it's ridiculous there's no second-degree murder," she said.

"Murder in this country has to be premeditated, you have to have meant to do it. They can say, 'We're just a bit thick and didn't realise that hitting him with metal rods and baseball bats would probably kill him'.

"It's not acceptable that you say, 'Oh but I didn't mean to actually kill him', and that's it. It's murder."