UPDATED 6.06PM The man who snatched a 5-year-old girl off the street and indecently assaulted her has previously been jailed in Australia for a similar offence.

Brendan Paul Henson, 47, was today sentenced to eight years in jail when he appeared in the High Court at Palmerston North on two charges of indecent assault and one of abducting a child for sex in February this year.

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His previous convictions and his actions when he snatched the girl in February can now be revealed. He admitted the charges at an earlier hearing but sentencing was delayed so preventive detention could be considered today.

In High Court at Palmerston North today, Justice David Collins decided not to impose preventive detention.

When he said that, a man in the public gallery swore loudly.

The man was removed after a further outburst and continued to swear loudly on his way out.

Instead, the judge jailed Henson for eight years.

He must serve at least five years behind bars.

For the first time a court summary of the offending can be revealed.

It says neither the girl nor her family had met Henson before February 10, when, at about 3pm, the girl and an older sister were playing in Takaro Park. 

Henson sat on a park bench, watching them.

He called the 5-year-old over and when she did, he touched her leg.

The older sister intervened and the two girls ran home.

"The defendant's vehicle was observed on nearby CCTV footage driving down Shamrock St following the incident. The victim and her sister can be seen running towards their home and the defendant's vehicle following, passing the camera about three minutes later," the summary says.

Hansen was again seen on the CCTV footage driving along Shamrock St about 8.20am on February 11.

He was back the same time the next day and spied the 5-year-old and her sisters.

"He pulled up next to them and opened the front passenger door before getting out and walking around to the victim.

"He picked her up and put her in the car while her sisters hit and kicked him and his vehicle in an attempt to save her."

Henson drove the girl to a "secluded location" in the countryside, parked and performed an indecent act.

He then dropped her off at Hind Place, Palmerston North.

A medical examination found traces of Henson's DNA, unravelling his identity.

In New Zealand, Henson has only one conviction, for cultivating cannabis in 1987.

But in Australia, he was convicted of aggravated sexual assault and indecent dealing with a child under 14. He served a year in a Western Australian prison in the 1990s.

The girl was the same age as the one he snatched and Henson was a boarder where the victim lived.

Collins said the offending was "devastating" to the girl and her family.

Henson said he was physically and verbally abused by a man until he was 11 and the victim of sexual offending by a neighbour when he was about 7.

Collins said he wasn't imposing preventive detention because Henson didn't meet the legislative test.

"You have displayed a desire to address the causes of your offending and participate in a special programme for child sex offenders."

However, during the abduction there was a "level of violence" when Henson snatched the girl. She was young and vulnerable and the offending was pre-meditated.

"You pursued the victim over a 48-hour period, possibly longer," the judge told Henson.

He detained the girl for two hours and what happened had a "catastrophic impact" on her emotional state and her family's too.

Collins said he could not give a discount because Henson decided during the offending it was wrong and dropped her off where she would be safe, as the defence claimed.

The judge added extra time for Henson's previous offending before offering discounts for pleading guilty and expressions of remorse.

In court today, Crown prosecutor Ben Vanderkolk said the victim was vulnerable because of her age. The most significant "aggravating factor" was the pre-meditation. He sought a 10- to 12-year jail term with a minimum non-parole period of half to two thirds.

Vanderkolk said the offending had had a "viral effect" on all three children involved and their mother and the way they live their lives.

Defence lawyer Fergus Steedman said he was sure everyone in the courtroom wished they could turn back the clock.

Steedman said Henson didn't want to read the victim impact statement at first, but his lawyer insisted.

"He was shocked. The full impact of what he'd caused on so many people didn't hit him until he read what the mother had to say."

Justice Collins suppressed the victim impact statement, which was read to the court.

Steedman said Henson understood he faced a long stretch in prison.

"I acknowledge that the defendant can be condemned roundly for what he did," Steedman said.

Henson had never been able to explain why he offended, which showed a lack of understanding and insight.

"The one positive I can say is, he's never said anything to me that to my ears sounded like justification."

However, he had made concerning comments to others, such as psychologists.

Henson was a "very private" person and it took a while for him to get to know people.

"It is apparent that in 2012 he suffered a major depressive episode. He was off work for about 18 months. He was deeply depressed for that period of time if not longer," Steedman said.

By February, it was becoming worse as Henson became more reclusive.

On February 10, "he saw a little girl and he just responded to her sexually".

"He made matters so much worse the next day and the day after when his actions culminated in an abduction."

In 1991, in Western Australia, Henson offended against another girl and was jailed for that.

Henson thought he'd managed to "bury the demons" in between times.

"I thought that it was a long time finished. I thought that I was normal again," Henson had said.

Steedman said he wasn't and had never had appropriate treatment.

Since the last offending Henson had three relationships with "age-appropriate" partners up until 2012.

His last partner was the mother of a little girl, aged between 4 and 8 when the pair were together.

"He thought that he was able to be a good father to his de-facto stepdaughter. He enjoyed being a good father to her. He is now appalled that having that opportunity he'd act in such an appalling manner in February of this year."

When Henson was alone with the 5-year-old he had "ambivalent feelings".

He said part of him didn't want to do what he did but he couldn't stop.

"It baffles me why I did it," Henson had said.

But Henson had a moment of clarity when something the 5-year-old said triggered him and he realised she was just a little girl.

"For the first time he was able to see, in his words: 'her whole self, just her whole being, the way she looked at me'. The next thought he remembers are these: 'What have I done? Why did I do that? I have to get her home'."

So Henson dropped the girl off on the other side of Palmerston North.

He thought it was the sort of area where responsible people could take care of her.

When he dropped the girl off he pointed out an older person gardening and told the girl to approach that person, say who she was and call the police.

Henson now had to do a huge amount of work to rehabilitate himself and he wanted to do that.

"He wants to make himself safe. He wants to change his life," Steedman said.

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