Wayne Harper was caught after he sold his Geelong home, and the buyer stumbled across a shoe left behind containing USB sticks of abusive pictures and videos.

Sickening conversations were also uncovered between Harper and other men.

At one point, the-then Marngoneet Correctional Centre general manager wrote: "Those little girls want sex just like we do".

The 58-year-old pleaded guilty in the County Court on Tuesday to five charges of possessing, producing and transmitting child abuse material between July 2015 and September 2019.

More than 1000 images and videos were found across his computer, mobile, iPad and an external hard drive.

Among the girls shown being abused was a two-year-old.

After police were called, Harper immediately confessed to his family, and said there was more abuse material on his work phone.

He also admitted using Instagram to share images of girls in bathing suits.

He told police he liked to discuss "forbidden" sexual fantasies with other people online.

Judge Patricia Riddell rejected a suggestion that Harper's exposure to "abnormal" sexual behaviours during his prison career contributed to his crimes.

The court was told Harper had previously worked with sex offenders and resigned from his role when he was charged last year.

Judge Riddell worried Harper remained in denial about his crimes.

"There's an element of kidding himself, to be frank," she said of Harper's suggestion that he had an intellectual interest in the deviancy of others.

He appeared preoccupied with the consequences for himself rather than the children who were abused, the judge added.

Sally Flynn QC said Harper had experienced a "spectacular fall from grace" and was committed to working on his problems.

She also said Harper was concerned about the possibility of other prison staff targeting him when he went to jail.

He was remanded in custody to be sentenced on November 13.

Australian Associated Press