But an ACT Supreme Court judge has rejected his claims that he recklessly opened the material while researching child behaviour.

The now former NSW and ACT police officer, who cannot be named, was found guilty at trial in September of three counts of accessing child pornography online.

But the jurors cleared the man, 40, of molesting a 12-year-old boy in his care and using the child to produce child porn in 2012.

During the trial, the court heard the officer had acted as a respite carer for the boy and his siblings.

Police raided their colleague's home after the boy accused the offender of molesting him, and found a computer on which someone had searched the term "boys" in a nudity section of a website, and entered "boys no undies" and "boys first time" into a search engine.

The offender said the boy had a habit of taking his clothes off and he had gone online to "research" the child's behavioural problems.

He said he had also searched the term "boys" because he needed images to add to disciplinary charts he was making for the children in his care.

But Chief Justice Murrell told a sentencing hearing on Wednesday that she had no doubt the man had accessed the porn intentionally.

"There was a deliberate entry of search terms to produce the material," she said.

But the judge said she accepted he had no intention of sharing or distributing the material.

A pre-sentence report rated him a low risk of reoffending, but said he remained in the denial stage.

But the report author said he had gained some insight into his offending.

The court heard he had been suspended from the force, now lived in Melbourne with his parents, was unemployed and had returned to tertiary study.

Chief Justice Murrell sentenced him to a one-year suspended jail term on entering a two-year good behaviour order, with a fine of $750.

The judge also ordered the man to complete the adult sex offenders' program if assessed to be suitable, and to continue counselling.