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No charges will be laid against Macsyna King, the mother of twins Chris and Cru Kahui, now that their father has been cleared over their deaths, police have said.

Chris Kahui was this afternoon found not guilty of the murders of the three-month-olds, who died in June 2006 as a result of massive head injuries.

His defence lawyers had argued that someone else - probably Ms King - was responsible for their deaths.

The officer in charge of the case, Detective Inspector John Tims, today said he was "disappointed" at the verdict and no more charges would be laid - including against Ms King.

"There is no new information that indicates anyone else is responsible for the death of the twins," he said.

"The Crown solicitor said in his opening and closing address that there is no new evidence to support a charge being laid against the mother, Macsyna King," Mr Tims said.

Jurors left the High Court at Auckland for lunch about 1pm, went into full deliberations at 2pm and emerged at 2.10pm with their verdict.

Mr Tims said nothing could be read into the mere 10 minutes that the jury took to return their not guilty verdicts.

He said he respected the decision but defended the police investigation.

"It has been tough investigation, a tough trial, it's been a tough two years," he said.

"I can honestly say that I've given 100 per cent, my team has given 100 per cent, and we can do no more."

Mr Tims said police were well resourced: "We had a committed team for four months not only once an arrest occurred, we still had a team working on the case."

But during the trial, arresting officer Detective Chris Barry said police were too busy with a wave of violent crime to re-interview Ms King about a development in the case.

Today, Mr Tims congratulated the jury who he said had sacrificed parts of their lives for the last six weeks.

"The last two years have been about Chris and Cru Kahui and nobody else and that has not changed, he said.

"We still have two twins, Cru and Chris, who no-one's been made accountable for their deaths."

Kahui reacts

When the final not guilty verdicts were given family members wept and hugged each other, visibly relieved.

As Mr Kahui looked overwhelmed his defence lawyers Lorraine Smith and Michele Wilkinson-Smith hugged and also fought back tears, hugging Mr Kahui.

While Mr Kahui was taken from the court to be released, family members remained in the public gallery in a circle, holding hands and praying.

Minutes later, Mr Kahui walked out of the court to a huge media scrum.

When asked how he was feeling Mr Kahui replied, "Good, real good."

Flanked by his family and his lawyers Mr Kahui, whom Mrs Smith had described in court as inarticulate, was clearly overwhelmed by the large media presence and at a loss for words.

When asked what his plans were Mr Kahui said he wanted to "try to start my life again".

Mr Kahui was asked what he meant but could not respond amid all the attention from the cameras and reporters.

Mrs Wilkinson-Smith came to Mr Kahui's aid, saying he was not able to think about what that meant.

A spokesman for the Kahui whanau said the family needed time to regroup after a difficult two-and-a-half years.

"Chris Kahui continues his innocence in the deaths of baby Cru and baby Chris and he is pleased he has been eliminated as a suspect.

"This is not a time to celebrate because the blood of two babies still cries from the grave for justice."

Kahui's eldest sister Tracey Still and his younger brother Elvis left the court without commenting to waiting media.

Mrs Smith said she was "very, very happy and very, very relieved" at the verdict.

But she added: "We must never forget that two babies have died, but this is what the system is all about and the system has worked."

Her colleague Michele Wilkinson-Smith said: "The Crown put their case up and we answered it."

Ms Wilkinson-Smith said she couldn't comment on whether anyone else would be charged over the deaths saying she was in court to defend Kahui.

Chris Kahui was asked who did hurt his sons and that was interrupted by Mrs Smith.

The evidence

The Crown case was that Kahui - under pressure and frustrated - attacked the babies mid-evening on June 12.

The defence disputed the timing of the assault, arguing it could have happened earlier in the evening and that someone else, probably the babies' mother, Macsyna King, was responsible.

Over the past six weeks jurors heard evidence that included more than 1300 pages of evidence and more than 60 witnesses.

Mrs Smith told them that the Crown case was made up of very thin strands of circumstantial evidence against Kahui and that there was a far more substantial case of circumstantial evidence against Ms King

"The Crown advanced a theory which is simply not capable of withstanding proof beyond reasonable doubt," she said.

In her summing up, Mrs Smith said no one heard the babies crying on the night the twins were allegedly injured.

"And if anyone had, the Crown would've brought that evidence to you with a 10-piece brass band," Mrs Smith said.

She told the jury that if medical witnesses could not be sure of when the injuries were inflicted on the twins, then neither could they.

"It is not a question of whether he may have done it but a question of beyond reasonable doubt," Mrs Smith said.

She also told the jury that they had been lied to about a cellphone call to Macsyna King's alibi, her sister Emily, on the night the Crown alleges the Kahui twins were fatally injured.

"It places her in Mangere, the very place where the twins are," Mrs Smith said.

She said Emily King first told police that the phone call could not be explained but later said she had been called by her partner who asked her to return the car.

Mrs Smith said there was a window of opportunity for Macsyna King to go home and find Kahui at the hospital before flying into a rage.

She went on to say that the return trip "did not make sense".

"The defence says you have been lied to by Macsyna and Emily King," she said.

The prosecution said

* Chris Kahui, 23, murdered his twin sons, Chris and Cru, when he snapped under pressure.

* The injuries were inflicted in a narrow time frame, meaning only he could have done it.

* Kahui didn't go with the twins to hospital even though he was told they were critically ill.

* He also didn't call an ambulance when Cru briefly stopped breathing.

The defence said

* The twins' mother, Macsyna King, inflicted the fatal injuries.

* She returned home and hurt them when she discovered Kahui wasn't there.

* Cellphone records show Ms King was in Mangere when she claimed she was in West Auckland.

* Defence lawyers Lorraine Smith and Michelle Wilkinson-Smith will call experts who will dispute Crown evidence of when the babies were injured.

- With NZPA