Child Youth and Family (CYF) is to review its involvement with two boys who took part in a fatal dairy robbery.
A 14-year-old, who has interim name suppression, was today sentenced to six years in prison for manslaughter and will serve at least three years and three months before being eligible for parole.
The second boy was cleared of the manslaughter of Arun Kumar, who died after being stabbed in his Henderson dairy in June 2014.
During the boys' trial, the court heard how there were 20 notifications to CYF during the 14-year-old's upbringing, half of which were for domestic violence.
In 2004 alone, social workers carried out three investigations into his family after concerns about the welfare of the boy and his siblings were raised.
There was also evidence his mother was using heroin and methamphetamine in front of her children and that the 14-year-old boy was hooked on synthetic cannabis and had stopped going to school.
CYF general manger of operations Paula Attrill said the investigation would be carried out by the agency's chief social worker.
Boy's problems began at birth - judge
At his sentencing today, the court heard how the 14-year-old's traumatic childhood and brain injury was blamed for causing him to lash out and stab a dairy owner to death.
But it was also credited for saving him from being convicted of murder.
Justice Lang said the boy's problems began before he was born with his mother's drinking putting him on the foetal alcohol spectrum.
At the time of the failed robbery, the boy had given up going to school.
He was just 13 years old and hooked on synthetic cannabis that was sold from the family home.
His mother tried to treat the addiction by giving him the real thing, while the boy's own brother described him as looking like a zombie when on the drug.
There was also evidence put before the court that the boy suffered from a brain injury after being hit by a car on a pedestrian crossing.
A specialist said any adult would have been off work for two years but this boy was sent back to school in two weeks with no rehabilitation.
Justice Lang said it was these factors which caused the boy to lash out and stab Mr Kumar during the failed robbery.
At a jury trial last month, the boy was found not guilty of murder but guilty of manslaughter.
But the judge also said he was left in no doubt that the boy would have been convicted of murder, if it were not for his medical condition that caused him to act on impulse.
Justice Lang said the boy's brain injury meant he couldn't deal with complex situations.
He said that was exactly what he faced when Mr Kumar refused to hand over money and Mrs Kumar brought out a phone for her husband to call police.
Justice Lang said the boy lashed out, and it was only bad luck that he stabbed Mr Kumar in the neck.
But in sentencing the boy, the judge said he needed to protect the community.
Today's sentence means the boy will not be eligible for parole until he is nearly 17 - the age at which he would be transferred to an adult prison.
Justice Lang said he hoped that if the boy did not get parole, the authorities would use their discretion and allow him to stay in the youth justice facility.
Victim's family avoids sentencing
The Kumar family chose not to attend today's sentencing or file victim impact statements, despite attending nearly every day of the trial.
Crown prosecutor Kieran Raftery said their pain was evident at trial and they did not feel they could put that into words.
During the trial they endured replays - sometimes in slow motion - of the CCTV evidence. Each time, Mrs Kumar could be heard crying in the back of the court.
Mr Raftery also said they found it particularly difficult to hear arguments from lawyers for the boy who argued their client was acting in self-defence when he stabbed Mr Kumar.
Justice Lang said he completely rejected any notion the boy was acting in self-defence.