The father accused of killing his nine-month-old daughter has been found guilty of her murder.

A jury returned a unanimous guilty verdict against Donovan Michael Duff just after 4pm on Tuesday, after around four hours of deliberations.

Duff, 42, had been on trial at the High Court in Rotorua for the murder of Maija Puhi-Duff and and always maintained his innocence of the one charge of murder over the infant's death in Turangi in 2016.

As the verdict was read out Rameka Puhi, the infant's grandfather, cried quietly in the gallery.

Justice Mathew Down thanked the jury for their service, telling the seven men and five women that "cases of this nature are very distressing".

He also paid tribute to Puhi.

"I express my sincere condolences for your loss. I thank you for the dignity you have shown," he said.

"As a father myself I can only guess how difficult this is for you."

It can now also be reported that earlier at the trial summing up Duff wore a hoodie in court featuring a photo of his daughter on the front.

Down also set a provisional sentence date of August 15 this year, and told Duff he would now be subject to the three strikes law.

Earlier, on the trial's seventh day both prosecution and defence lawyers made their final summations to the jury of seven men and five women.

Even Crown prosecutor Amanda Gordon said Duff loved his daughter.

"It's very clear that Maija was loved by many, many people. She was her grandfather's heart, and she was loved by the defendant, and he was by all accounts up until this day [the day she died] a good dad," Gordon said.

"He was not a good dad on the evening of Friday March 11 and the early hours of Saturday."

Gordon's summing up referred to expert evidence given by forensic pathologist Dr Dianne Vertes, who conducted the post mortem on the infant, neuropathologist Professor Colin Smith and Lori Frasier, Professor of Paediatrics at Penn State University in the United States.

She said all three were "unshakeable" in their view that Puhi-Duff's death was not caused by a fall from a bed, an earlier fall or the cumulative effects of these falls.

She said Crown evidence clearly proved the cause of death to be a brain injury, the time the injury was sustained and that only Duff was with his daughter at the time.

"When the injuries occurred there is only one answer to who [inflicted them]... it was only the defendant who had the care of Maija during that time."

Gordon also cited expert evidence about the brain injury the infant suffered to rubbish claims they could have been caused earlier, saying she would have been rendered unconscious almost immediately.

Gordon raised the issue of Duff's failure to call 111 when he awoke to find her unresponsive.

"He knew what he had done, and that's why he didn't call 111," she said.

"Good people can do bad things and on this occasion, the defendant did a very, very bad thing."

Duff's lawyer Moana Dorset began her summing up by casting doubt on the expert testimony.

"What they've not told us is how that blunt force trauma was caused, they've told us how they think this blunt force trauma was not caused."

Dorset said she believed the cause of Puhi-Duff's fatal injury was still a fall from the bed she suffered on the Friday night before her death.

She was particularly critical of the Crown use of evidence from Frasier - an expert in child abuse.

Dorset said Frasier was "invited by the Crown to give her verdict on abuse" but could shed no light on whether Duff committed the fatal assault.

"Assumptions and presumptions and created a scenario designed to convince you he assaulted this child..her job is to bolster the Crown's case," she said.

She also took aim at some of the language used by the expert witnesses.

"Possible doesn't cut it, probable doesn't cut it, unlikely doesn't cut it. These are words that can't hit the high standard of unreasonable doubt," she said.

Dorset also said Duff consented to an autopsy for his daughter immediately, and said there was an explanation for the lack of 111 call - he already knew she was dead.

She also said he was happy to speak to the police in the wake of his daughter's death.

"Mr Duff trusted the police to help him and instead, was charged with murder," she said.

"If you're not satisfied beyond a reasonable doubt, find him not guilty."

Dorset also told the jury that the onus of proof remained with the Crown.

"I don't need to remind you what a monstrous mistake it would be to find a man guilty of murder...you know the proper verdict of this case. It's not guilty."

In his final summing up, Down warned the jury against letting emotion cloud their thinking.

"The fact it involves an infant heightens that risk," he said.

He also warned them not to draw any conclusions from the fact Duff did not testify, and said anyone before the court is entitled to the presumption of innocence.

"Mr Duff need not prove anything, let alone innocence."

- Stuff/ BENN BATHGATE