A youth worker has been jailed for two years and six months for sexual conduct with a 14-year-old girl who was being held in a secure facility near Christchurch.

Phillip Lavea, 26, who has a young family, continues to deny the offending but was found guilty on four charges at a Christchurch District Court jury trial last month.

Another girl from the same facility gave propensity evidence of similar conduct by Lavea.

Lavea was aged 23 or 24 at the time of the offending.

The jury was able to see a letter he had written to the complainant. It was not contested at the trial that he had written it, and the judge said it gave a window into his mind.

Defence counsel Craig Ruane said it appeared that "getting on with an attractive staff member might be seen as a feather in the cap" among the facility's residents.

But Judge Saunders said: "That's the very thing that he [Lavea] and other staff members have to guard against."

Ruane said Lavea, as a youth worker, had found he had empathy to deal with young people, get on with them, and interact with them.

"Writing the letter shows a lack of judgment and understanding of consequences and boundaries," he said.

"It shows naivety, immaturity, and simple lack of understanding."

The offending appeared to have occurred over about three weeks.

"Other than that he seems to have been well respected and to have good supports in the community."

Lavea was no longer working in the youth area, but had another job to return to.

Crown prosecutor Catherine Butchard said there were "troubling aspects" for a pre-sentence report in which Lavea did not acknowledge his responsibility for the offending.

Judge Saunders said the offending had been a breach of trust, against a girl who was in secure care and unable to leave the facility.

"You were aged 23 and supposed to be acting as an adult in a position of trust. You should not have breached the protocols that were clearly there to protect you and the complainant."

- © Fairfax NZ News