Luke Braden Taylor, 31, first encountered child abuse material on cases he confronted while a police constable on Sydney's northern beaches.
After passing the disturbing matters up the chain of command to detectives as was protocol, the former officer was interested to know what kind of content he was handling, he told Parramatta District Court on Thursday.
"With other jobs that I would attend I would see most of them throughout the investigation and be involved in all of the steps," he said.
"I was just curious in nature, which I know isn't an excuse, but yeah."
His curiosity led him to a chat on the messaging app Kik, where he clicked links to folders full of sexual imagery and videos of children, some of them as young as 12 weeks old.
One of these folders was more than 19 gigabytes in size - taking up about as much hard drive space as an ultra-HD feature film.
That folder contained "1000 images of highly depraved content", crown prosecutor Edward McGinness told the court.
But Taylor said he only viewed a small number of files before quickly deleting the app they were visible on, never downloading them.
"It was never for the purpose of sexual gratification, looking at the material," he said.
"Its still not acceptable, but it was a curiosity, not to fulfil sexual desires or anything like that."
The 31-year-old testified he was "disappointed in (himself)" each time he viewed the files, with his barrister Ann Bonnor relaying "he stopped because he felt sick about viewing the material" in her submission to the sentencing hearing.
But similar cases Taylor encountered in the line of duty would reignite his curiosity four more times over the next two-and-a-half years.
Each time, he re-entered the Kik chat, clicked on a link to view a small amount of abuse material and deleted the app, he told the court.
Although testifying he has no sexual interest in children, Mr McGinness submitted Taylor's actions could not be explained by curiosity alone.
"You accept it has to be a quite a strong desire to overcome that sick feeling," Mr McGinness told Taylor.
"Yes, yes," the former constable replied.
Taylor's explanation was poorly elaborated and he had not explored his sexuality well enough to rule out an interest in children, Mr McGinness said.
He also continued to offend despite, as a police officer, knowing the seriousness of his actions.
"You need to be alive to the very real possibility that you may be spending some time in custody," Judge Karen Robinson told Taylor as the hearing concluded.
Taylor is scheduled to be sentenced on June 19.
Lifeline 13 11 14
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
National Sexual Abuse and Redress Support Service 1800 211 028
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