A grandmother convicted of murdering her two-year-old grandson has been sentenced to life in prison with a minimum non-parole period of 14 and a half years.
Kathleen Elizabeth Cooper, 65, was sentenced this morning at the High Court in Auckland after being found guilty of murder on August 15.
Justice Katz said it will never be known exactly what Cooper did to Jermain Ngawhau but it's likely she threw him down a hallway at their Manurewa home in December 2015 and he died of his injuries five days later.
The Judge said Cooper had taken on the huge responsibility of caring for her four grandchildren.
The judge also said she smoked methamphetamine in the garage with friends in the week leading up to the murder.
But Justice Katz said it was the stress of caring for four children under five years old, and Jermain's special needs, that tipped Cooper over the edge.
After a toileting accident, Justice Katz said it was likely Cooper used extreme force by throwing him down the hallway.
Ms Cooper later blamed one of Jermain's siblings for the attack and lied to police, medical professionals family and friends before owning up shortly before her trial.
Crown prosecutor Aaron Perkins QC earlier asked the court to impose a sentence of life in prison with a minimum non-parole period of 17 years.
Mr Perkins told the court while it is not absolutely clear how Jermain was killed, the fact that a large amount of force was used is certain.
He said fresh bruising on Jermain showed there was likely previous injuries.
Mr Perkins told the jury this year that Ms Cooper would discipline the children by "smacking them in various different ways".
"A number of witnesses, particularly staff at daycare centres, noted quite regular and often quite significant bruising on the children," he said.
Justice Katz said it was an appalling breach of trust when a child is killed by the person put in charge of their care.