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A former carer of a toddler beaten to death yelled to his killers "go hang yourselves" when they were sentenced in the High Court in Auckland today.

Otara couple Maine Ngati, 32, and her partner Teusila Fa'asisila, 27, were jailed for eight-and-a-half years - with a non-parole period of four years and eight months - for the manslaughter of Ngati's son.

Three-year-old Ngatikaura Ngati died after a severe and prolonged beating by his mother and step-father on January 30 and 31, 2006.

Ngati and Fa'asisila appeared for sentencing after last month being convicted of manslaughter, failing to provide a child with the necessities of life and wilful ill treatment of a child.

Ngati's cousin Kura Kaufusi, who had had care of Ngatikura but lost custody in November 2005, yelled at the pair to hang themselves as they were led away from the dock at the end of the sentencing.

Her comments sparked a fierce war of words between her supporters and those of Ngati.

Ms Kaufusi's brother had to be restrained by supporters and police inquiry head Richard Middleton told both parties to "show some dignity for Ngati (the boy)".

Ngatikaura's great-aunt Nina Ngati said outside the court the sentence "sucks" and she was still unhappy at the manslaughter verdict.

"The sentence is not long enough for them to go inside for murdering my grandson," she said.

"My daughter put him up for three years and then they took him from us. It was not God who took my grandson, it was the system."

Judge's decision

In court today, Justice Graham Lang told the pair they had abused a position of power by beating Ngati's son, a fact made worse by the use of weapons, which included a baseball bat.

They also failed to get Ngati medical treatment, which could have saved his life in the hours before his death.

Justice Lang said he accepted Maine Ngati was under stress and possibly suffering from post-natal depression when Ngatikaura arrived, and that she and Faasisila did not intend to kill the child.

However, he said their idea of how to discipline a child was completely unjustified.

"Ngatikaura was robbed of his life even before it had properly begun," the judge Lang told the pair.

"It was incumbent upon you to protect him from harm. Instead you did the very opposite."

Judge Lang said his sentence was guided by principles from a previous Court of Appeal judgment that the manslaughter of a defenceless child was more serious than that of an adult.

The starting point for the sentence was 11 years for Ngati and 10 years for Faasisila, the latter given an allowance for making more of an attempt to get medical treatment for Ngatikaura.

Judge Lang gave both an allowance for circumstances and a relatively clean record prior to this case.

Judge Lang also sentenced both to four years jail for failing to seek medical treatment and 18 months jail for wilful ill-treatment, sentences to be served concurrently with the manslaughter sentence.

Jury trial

A jury in the High Court at Auckland in May found Ngati and Faasisila, not guilty of murder but guilty of the manslaughter of Ngatikaura.

The couple, who lost name suppression once the verdicts were delivered, were also found guilty of wilful ill-treatment and of a separate charge of manslaughter for failing to seek quickly enough medical care which could have saved the boy's life.

Some of the jury of seven women and five men had tears on their faces as they returned after deliberating for 4 1/2 hours on a three-week case which Justice Graham Lang said must have been a harrowing experience for them.

The boy died in Starship children's hospital in Auckland after being taken from his home the day before unconscious and covered in bruises, with a particularly swollen left arm.

He had been in his mother's care for less than three months, was unable to speak much English and had constant problems with bedwetting and soiling his pants.

Crown prosecutors Ross Burns and Claire Ryan said the child died due to extensive soft tissue injury caused by beatings he received because of his toilet training problems.

They also alleged that Ngati and Faasisila did not seek medical treatment for the boy because they feared his bruises would implicate them.

- Additional reporting NZPA