A father who smothered his 2-year-old daughter to death with a pillow will be freed from prison - despite still maintaining her death was "an accident".

Philip Murray Kinraid was convicted and jailed for the manslaughter of Esme Claire Kinraid at their Hawera home on June 26, 2015.

On an undisclosed date this month he will be released.

The Taranaki father of two was putting his children, including a crying Esme, to bed and wrapped his daughter in a blanket.

However, Esme kicked it off, which led to the burly man flipping the toddler over and placing her face down on a pillow. He then pressed down on the back of Esme's head with his arm.

In November 2016, the chemical engineer pleaded guilty to the toddler's manslaughter - but only after a judge ruled evidence for a murder charge was inadmissible.

Police had obtained medical records which detectives said proved murder, however, the records were excluded because medical privilege applied.

A court order prevents the Herald from publishing specific details of the evidence, however, it is understood the Crown was relying heavily on it to prove the murder charge.

On February 22 last year, Justice Rebecca Ellis sentenced Kinraid in the High Court at New Plymouth to four years and three months' imprisonment.

He appealed his sentence in the Court of Appeal, claiming it was "manifestly excessive", but the challenge was dismissed.

This month, after serving the minimum required third of his sentence, Kinraid was released from prison.

Following a Parole Board hearing on July 9 at Tongariro Prison, the board found Kinraid had a "favourable parole assessment report and a new partner".

"He has approved accommodation with [withheld] and strong family support of [withheld]," the report reads.

A psychologist's report from May found "no further treatment was warranted" for Kinraid because "he had made exemplary progress" with one-to-one counselling.

"He is assessed at low risk but there is some need to strengthen his release plan," the parole board said.

"Mr Kinraid has no previous convictions and the offence was inexplicable. Although, as he says, the death of his daughter was 'an accident', his actions, which caused that death, were unlawful and very serious."

After sentencing, the detective in charge of the case, Daniel Coomey, told the Herald he couldn't comprehend how Kinraid's actions could be conceived as an accident.

"Most definitely not," he said.

"No length of time served in prison is going to lesson the harm caused by Mr Kinraid."

The report added Kinraid has completed anger management treatment, grief counselling and parenting courses.

"Weighing up all factors we have reached the conclusion that Mr Kinraid meets the statutory criteria for release on parole as he would not pose an undue risk to the safety of any person or the community generally, provided he faithfully complies with the conditions of parole," the board said.

Kinraid was transferred to the South Island to serve the remainder of his sentence before being released so he could be closer to his family.

At his sentencing, the court heard how Esme began "squirming, making noises, inhaling and exhaling while she screamed" as her father pressed down on her.

After suffocating Esme, Kinraid left for work and later told police it appeared his daughter was breathing normally.

He returned to watch videos with his partner, but when he checked on his children he found Esme "unnaturally stiff" and colourless.

"You turned her over and noticed one of her eyes was half open," Justice Ellis said.

After attempting to perform CPR on his daughter, Kinraid rang 111.

"I think I may have killed my daughter," Kinraid told the operator.

Crown prosecutor Justin Marinovich told the court: "The horror that Esme must've felt in the last minutes of her life when her face was held into the pillow and her life taken away ... there is no doubt in her last minutes she experienced true horror."

Justice Ellis said the cause of Esme's death was a "fatal neck compression" and that the toddler had "no chance of escape".

"Esme is dead, her life and her future were taken away in an instant," the judge said.