An elaborate undercover operation was used by police to gain a confession in the case of a baby girl fatally shaken by her father.
Tawera Wichman was sentenced in the High Court in Wellington today and jailed for three years and 10 months for the manslaughter of baby Teegan in 2009.
Teegan was the younger of twins born to Wichman and his girlfriend when they were 17 and 16 respectively.
Justice France said Teegan was the more difficult baby; she didn't sleep well and cried a lot.
He said on 4 March 2009 Teegan's mother drove to her parents to seek help.
While she was away, Wichman tried to give Teegan a bottle to comfort her, but she continued to cry and he shook her.
The baby's head did not come into contact with anything but she lost consciousness and Wichman immediately called an ambulance.
Teegan was flown to Starship Hospital in Auckland for treatment and was released after two months, but she was readmitted to Hutt Hospital in May 2009 and remained there until her death.
She died in September 2009, a month short of her first birthday.
Initially Wichman denied responsibility for the child's injuries and the investigation stalled until a five-month operation began in 2012, in which he was initiated into what he thought was an organised criminal group.
The group were in fact all undercover police officers.
Over 21 scenarios played out, including Wichman's involvement in car repossession operations and delivering drugs.
He was paid up to $300 a job and travelled around the country to work for the group.
Wichman was told the group was like a family, founded on trust, loyalty and honesty, and its boss could fix members' problems with police.
Eventually he was introduced to the 'boss', who told him he had to be sure Wichman would never lie to him or deceive him.
It was at that meeting that Wichman confessed to shaking baby Teegan.
The operation was the subject of three court hearings.
The High Court ruled information gathered from it could be used if the case went to trial, but that decision was overturned by the Court of Appeal.
The Crown then took the case to the Supreme Court, which upheld the earlier High Court decision.
Detective Inspector Scott Miller, who led the investigation, said outside court today the undercover programme was a very valuable tool in the fight against child abuse, regardless of how much it cost.
Wichman had 'genuine remorse'
Justice France said Wichman had suffered serious consequences.
He said the other twin had been removed from the parents' care, and Wichman's pending jail sentence had caused the loss of a business he took over from his father.
Justice France said it was not one of the worst cases of child abuse and it would be wrong not to recognise the difficult situation the young couple were in.
It was a case of loving parents, probably out of their depth, making a mistake not from anger but from frustration.
Reducing the sentence to recognise that did not condone what happened, but reflected that an offender's blameworthiness could vary, Justice France said.
It took Wichman seven years to acknowledge he was the cause of the brain injury.
"While that does him no credit at all, he does today acknowledge responsibility and has genuine remorse, not just for what happened, but the wider consequences."
Wichman's lawyer, Paul Paino, told the court his client was ill-equipped to carry out the parenting duties required for twins released from hospital after being born 15 weeks prematurely, but a probation officer assessed Wichman as being at a low risk of reoffending.
As Wichman left the dock several of his supporters in the gallery called out "love you".
Teegan's short life
The babies spent three months in the neo-natal unit at Wellington Hospital under specialist care after they were born, partly because of their frailty but also because of concerns about their parents' ability to cope.
Initially they had some Child Youth and Family assistance and help from a roster of family supporters who helped care for the twins and did household chores, but, by the time Teegan was injured, Wichman and his girlfriend were mainly caring for the children by themselves.
Baby Teegan's maternal grandfather, Lance Tairoa, read a statement to the court in which he spoke of the shock he felt when told of her injuries.
He flew to Starship Hospital and was present when she woke from a coma.
"I said 'hello my angel, it's Granddad here'. She opened her eyes and the nurses gathered around her. [They] were praising her saying 'we now know what colour her eyes are. She is beautiful. She... knew your voice and came out of the coma because she knew her granddad'."
Detective Inspector Scott Miller urged members of the public to speak up if they suspected child abuse was occurring in their neighbourhood.
He said Teegan's twin brother and a younger sibling had been in the care of Child, Youth and Family since her death, and were living with a good family.