Ariah Roberts killing: Mum gives evidence in murder trial over Mangawhai toddler's death

Ariah Roberts was sick on the day of her death, but there was nothing out of the ordinary, a court has heard.

WARNING: GRAPHIC CONTENT

Ariah Roberts' mother has fought back tears, describing the moment she found out her daughter was dead.

Her then-partner, Aaron Archer, is on trial – charged with murdering the 2-year-old on August 22 last year at their Mangawhai home.

Ariah's mother, who cannot be named, took the stand today and said she was out of the house no more than 15 minutes before Archer phoned her saying the little girl wasn't breathing.

She raced home, found her daughter covered with a dressing gown, and ran to neighbours who called the ambulance.

While they were waiting outside, she heard Archer tell her mother he'd been "chucking her up in the air" when she hit her head.

"He just said she'd hit her head. He didn't say what on," she told the court.

While the Crown alleges Archer killed the toddler, his defence says she died after being accidentally swung into a wall while the two were playing.

Ariah's mother told the court that Archer and Ariah got along fine and she'd seen him do this before.

"I'd swing her round sometimes too, by her hands," she said.

She said she wouldn't have someone in the house who was dangerous — Ariah was her "miracle child", so she was very protective of her.

She said her daughter was sick on the day of her death, but there was nothing out of the ordinary.

Aaron Archer appears in the Auckland High Court accused of murdering 2-year-old toddler Ariah Roberts. Photo / Jason Oxenham

Archer, 30, is on trial in the High Court at Auckland before Justice Christian Whata and a jury.

He conceded he caused the child's death but claims it was accidental, and has pleaded not guilty to murder.

Earlier today, the court heard from forensic pathologist Dr Rexson Tse - who completed Ariah's autopsy.

He said the child had 20 bruises about the head alone when she died and that he believed she died from blunt force injury.

He said her injuries aren't normally seen in toddlers of normal, daily knocks and bumps.

"The number of bruising, it's over 20. It's focused on the head region. There are no bruises on the limbs. It's on all sides of the head and more than 1cm large," he said.

Yesterday the court heard the multiple "blunt force" blows to the little girl's head were comparable with a car crash, multi-storey fall or being hit with a cricket bat.

University of Edinburgh neuropathologist Professor Colin Smith said her cause of death was clear.

"The information is that there were multiple bruises over the head ... Bruises are clearly a sign of impact, the head has hit against something.

Ariah Roberts was sick on the day of her death, but there was nothing out of the ordinary, a court has heard.

"This is an injury that was non-survivable ... in this case you could have the best neurosurgeons ready to go [but] this was a devastating head injury."

Last week the jury heard from emergency services responders who were first at the scene after Ariah was allegedly murdered.

And they heard from the neighbours who raced to the house where Ariah was living after hearing her mother "hysterical" in the driveway "screaming" that the child was not breathing.

The jury will also hear from a number of experts who will speak to Ariah's fatal injuries and explain why, in their opinion, Archer's explanation of her death "does not add up".

He says he was swinging her and accidentally dropped her or hit her head into a wall.

However, the Crown alleges he subjected her to a brutal assault that left her with head injuries comparable to a high speed car accident or fall from at least two storeys.

The trial continues.