Liam Chappy Nixon, 27, was also found in possession of 1485 videos and 53 images of child sex exploitation as a result of a trans-Tasman police investigation that began last year.
Nixon appeared before Judge Jim Large in the Greymouth District Court yesterday for sentencing on 10 charges of sexual abuse and online sexual material, relating to four victims, between 2016 and 2022.
The offending included indecent assault on one boy when he was 10, and sexual connection with the same victim while still under 16.
Nixon also admitted possessing and distributing child exploitation material, involving male victims in New Zealand and Australia.
His victim, now aged 14, told a closed court that Nixon had been a family friend, and someone he looked up to as a role model.
"I now get nightmares a lot. It's disgusting what he did to a little boy — that was me."
Appearing via audio visual link, the boy said he used to attend St John but quit after his first encounter with Nixon.
"Before he moved to my town I was doing really well at school. I started smoking drugs after the first time he did something to me."
The victim said he had taken up drugs to stop the images of what Nixon had been doing to him and "escape reality".
Nixon also filmed their sexual interactions over several months when the boy was aged 13 and 14.
Between 2016 and 2018, the victim would visit Nixon to hang out socially, often playing video games.
One day in 2018, Nixon reached out while the victim was sitting on the couch and stroked the side of his buttocks. The victim, then 10, reacted by getting up and leaving and hiding in the bathroom.
Between this offending and 2021 no more contact offences occurred, and the victim moved away.
That year, Nixon took the victim and his older brother on holiday. Nixon bought the victim sweets, cigarettes and took him out for meals. In the evening, as the older boy slept, Nixon sexually assaulted the victim.
Between May and December 2021, Nixon engaged in a sex act with the victim, and engaged in further sexual activity between January and September 2022.
The victim was 13 and 14 at the time; Nixon was 26 and 27.
Nixon's lawyer Hannah Stuart said Nixon claimed he was in love with the young boy at the time and viewed the relationship as "normal".
"Obviously in the light of day that is wrong, and he's the first to admit it," Ms Stuart said.
"This isn't a case of targeting someone because they were young. He was motivated by feelings for the victim, but with that is an unhealthy interest in younger people."
Nixon's phone contained a large amount of objectionable materials including naked images of other boys as young as 8.
A police investigation was launched after Nixon shared one of the images on Snapchat.
Police searched his home in September last year. A hidden, secure folder on his cellphone contained 15 individually named folders, 11 of them containing objectionable material.
Nearly all the material related to young boys aged between 8 and 15 years old engaged in various sexual acts.
The Crown summary of facts says three other teenage victims were also identified in the explicit material saved to the phone.
The folders containing objectionable material that did not relate to identifiable individuals were sourced from online channels and contained large quantities of material.
Crown prosecutor John Whitcombe sought a starting point of seven years' imprisonment.
"It's had lasting impacts on the victim who was a very young child, and it occurred over a lengthy period of time where he should have been growing up."
The strength of the evidence was "overwhelming" given the videos and images found on Nixon's phone, Mr Whitcombe said.
Judge Large said the filming of the offending was an aggravating factor.
"Your young victim was offended by you in a most graphic and totally inappropriate way. It may be you were in love with him but that does not justify or in any way excuse your behaviour for the damage you've done to that young man."
The judge made reference to the work Nixon had done in the community with his former role at St John.
"While you were doing good things in the community you were also acting totally inappropriately against your victim. He was a young boy and you took advantage of him for your own sexual gratification."
Ms Stuart sought credit for Nixon's guilty plea and remorse.
Judge Large acknowledged this and said the guilty plea had also spared his victim from having to face a court trial.
Judge Large eventually settled on a sentence of three years and 10 months in prison, with no allowance given for Nixon's time spent on remand.
Police also asked for Nixon to be registered on the Child Sex Offender Register upon conviction.
West Coast investigations manager, detective senior sergeant Kirsten Norton commended the bravery shown by the victims to come forward.
"We acknowledge the significant trauma and long-lasting effects these incidents will have on the victims and their families. Despite a result in court, these traumatic events will be with them for the rest of their lives."
She also thanked officers involved in the case for their efforts to ensure Nixon was held to account.
"This result came from tenacious work by detectives in Greymouth and colleagues around New Zealand, and colleagues in the Australian Federal police too."