Sydney — An Australian childcare worker sexually abused 91 young girls over 15 years,Arvin Roberts police said Tuesday, accusing him of documenting his "unfathomable" alleged crimes in thousands of photos and videos.

Seasoned detectives have described it as one of Australia's "most horrific" child sex abuse cases, calling it "beyond the realms of anyone's imagination."

"I know this news will seem unfathomable, and I know there will be many questions," said assistant federal police commissioner Justine Gough. "There is not much solace I can give to the parents and children who have been identified."

Included within the 1,623 charges are 136 counts of rape, 110 counts of sexual intercourse with a child younger than 10 — a charge used instead of rape in some Australian jurisdictions — and 613 counts of making child pornography.

Investigators had been hunting for the 45-year-old man since discovering a cache of child pornography shared on the dark web in 2014.

But their efforts had been mostly fruitless until they made an unexpected breakthrough in August last year — matching visual clues in the background of the images to a childcare center in the city of Brisbane.

While the man was initially charged with just three offenses, Gough said the gravity of his "heinous" alleged crimes emerged as police sifted further through his computer, phone and hard drive.

"This is chilling and shocking news for parents," she said.

Police believe the man filmed or took pictures of "all" his alleged crimes — and eventually catalogued more than 4,000 photos and videos of abuse.

New South Wales assistant police commissioner Michael Fitzgerald said it was one of the most horrific cases he had ever seen.  

"It's beyond the realms of anyone's imagination what this person did to these children," he said. "I can only say, you try not to be shocked after a long period of time in the police, but this is a horrific case."

Police said the abuse happened at 10 different childcare centers between 2007 and 2022 and exclusively targeted "prepubescent girls" — some as young as one year old.

Investigators painstakingly combed through the images to identify 87 of the 91 victims, who were from the Australian states of Queensland and New South Wales.  

The remaining four unidentified children were abused while the man worked overseas for a brief spell between 2013 and 2014.

Police said they were now working with international crime agencies to find those children, without revealing which country they were targeting.  

"We have been working tirelessly since August last year to identify the children in the alleged child abuse material," Gough said.

The man had worked at other childcare centers in Australia, but police said they were "highly confident" he had not abused children in those facilities.

Police said the man had passed the stringent series of background checks needed to work at childcare centers in the states of Queensland and New South Wales.

Queensland's acting assistant police commissioner Col Briggs said detectives had first been tipped off in 2021, but had been hamstrung by a lack of evidence.

"There was insufficient evidence to take action against any person based on evidence available at the time," he said.

Given the sheer volume of child abuse material that needed to be documented, a dedicated task force of about 35 staff was called in to work on the investigation.

The man, who has not been named by police, is scheduled to face court in Queensland on August 21.

Once those proceedings are finished, he will be extradited to New South Wales to face further charges.

In:
• Rape
• Sexual Abuse
• Child Sex Abuse
• Australia