A jury has heard a man accused of murdering a Mangawhai toddler told his neighbour he accidentally dropped the girl.
Two-year-old Ariah Dawn Roberts died in the care of her mother's former boyfriend, Aaron Archer, in the early evening of 22 August 2018.
Mr Archer is on trial in the High Court at Auckland this month accused of murdering the toddler, who died of a fatal brain injury.
Steve and Helen Taua were watching television when they heard "hysterical" screaming coming from their rental property in front of their home.
Mr Taua said the pair ran towards the house and found the mother standing on the driveway and Mr Archer holding the toddler.
"[Ariah's mother] said she wasn't breathing so I grabbed the baby and started CPR. I noticed she was cold and had vomit on her."
Mr Taua cleared the toddler's airway and worked on the girl until paramedics arrived but the two-year-old died shortly afterwards.
Today he told the jury Aaron Archer said he was playing with the two-year-old when she hit her head.
"He said he was swinging her around and accidentally dropped her or she hit her head somewhere ... I can't be exact honestly I was really focused on trying to bring the baby back.
Helen Taua - who helped her husband perform CPR on Ariah - recalled Mr Archer saying he dropped the girl.
"He just said she hit her head ... He used the phrase 'I dropped her, she hit her head'.
It's the Crown's case that Mr Archer assaulted Ariah while he was alone with her; inflicting injuries that can't be explained by an accident.
Crown prosecutor Olivia Klaassen said the toddler was uninjured - bar a single bruise to her eye - when her mother left home that night.
The told the jury when the woman returned Ariah had around 20 bruises on her head and face and a fatal brain injury.
"The level of force required in a head injury for a child of this age is equivalent to that of a road traffic accident or falling from a height of around two storeys."
Ms Klaassen said Mr Archer's explanations of what happened that night didn't match up with the expert evidence.
She told the jury they would hear from a forensic expert who found Ariah's injuries could only be caused by deliberate force.
In a brief opening address, Mr Archer's defence lawyer Annabel Maxwell-Scott said her client didn't assault the girl.
"There is nothing sadder than the death of a child. None of us wish we were sat here dealing with this but we have to.
"The defence case is simple; it was an awful tragic accident but it was an accident."
She later asked Steve Taua about Mr Archer's demeanour at the house that night.
"He was traumatised as well, there's no doubt about that. It must have been pretty tough for him too."
Over the next two weeks the jury will hear from 29 Crown witnesses including first responders, international forensic experts and Ariah's mother.