Aaron James Archer killed his girlfriend's 2 year old daughter at their home in Mangawhai in August, 2018.

A man who killed his girlfriend's 2-year-old daughter by swinging her into a wall has previous family violence convictions, a court has heard.

Aaron James Archer appeared at the High Court at Auckland on Monday where he was sentenced to seven years and three months in prison for the manslaughter of Ariah Dawn Roberts, who died from severe head injuries.

Archer was cleared of her murder and instead found guilty of manslaughter, after insisting Ariah was injured accidentally when she hit a wall as he lost grip of her while swinging her around.

The 31 year old will have to serve at least half of that sentence before being eligible for parole.

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* The jury returned a majority verdict on Thursday afternoon, after almost two days of deliberations

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* Aaron Archer murder trial: Grandmother saw bruises days before 2-year-old died

* Aaron Archer murder trial: toddler killing accused leaves message of apology on mother's phone

* Aaron Archer murder trial: two-year-old's head injury was 'catastrophic'

Evidence of Archer's previous convictions for three family violence incidents and one common assault were never put to the jury.

On Monday, Justice Whata said they would not result in an increase in his sentence but the judge said they would be a factor in determining a minimum non-parole period.

The judge said Archer's childhood was marred by violence with his father was jailed twice for serious offending.

Archer was diagnosed with ADHD and dyslexia and left school in the fourth form.

Archer has three children himself, two of which are in the care of Oranga Tamariki, the court heard.

Justice Whata said while Archer admitted he was responsible for what had happened to Ariah, he maintained her death was an accident.

"Quite clearly, Mr Archer is remorseful for having caused the death of a young girl but ... he continues to deny culpability in causing intentional harm."

The judge said Ariah was a vulnerable child, who was left in Archer's care for a matter of minutes on August 22, 2018, while her mother nipped down to the shops.

"Ariah's head was struck with brutal, catastrophic force."

The judge said while Ariah had other bruises on her head, he concluded she was killed by a single act of violence.

David White A blue tarpaulin covers the front of the scene where toddler Ariah Dawn Roberts was killed

Archer told the judge in a letter he wished he could "undo" what he had done.

Justice Whata also referred to a statement from Ariah's maternal grandmother who said the death had effected her mental health and emotional wellbeing.

She told the court nothing could atone for the loss of her granddaughter.

In sentencing, Justice Whata gave Archer a reduction for his capacity to rehabilitate and acknowledged the steps he had already made while on remand.

At Aaron Archer's trial in September, Crown prosecutor Brian Dickey held up a photo of Ariah's bruised head for the court to see.

"No child should look like that. No child," he said.

Archer had moved in with Ariah and her mother six months before the toddler died. The three shared a small two bedroom house in Mangawhai, north of Auckland.

The court heard Ariah had fatal head injuries similar to those of someone who had been dropped from a three-storey building.

DAVID WHITE/STUFF Police outside the Mangawhai house where Ariah Dawn Roberts was killed.

Archer's first reaction was not to call 111 or go to neighbours for help, but to put Ariah's body on a bed, cover it with a nightie and phone Ariah's mother.

Ariah's mother missed the phone call but Archer left a message, recorded on her voicemail, apologising for what had happened.

Archer's lawyer Ron Mansfield told jurors the recording showed just how distraught his client was.

"You can hear in the call what was going on with Mr Archer ... you can hear how upset and distraught he was ... how he wasn't thinking," Mansfield said.

"You can hear him calling out in the most haunting of ways: 'Breathe, come on, breathe'."

During the trial, the jury heard a pathologist found 20 bruises on Ariah's face and head, and the results of an autopsy found she died of a brain injury, following multiple blunt force trauma injuries.