Police admit they made errors handling a complaint about a convicted rapist weeks before he allegedly sexually assaulted a seven-year-old girl at a Sydney dance studio.
Politicians and police top brass are pledging to stop it happening again.
An internal police investigation has revealed a woman filed a complaint about an offensive call from 54-year-old Anthony Sampieri at St George police station on October 26.
At the time Sampieri was on parole after being jailed for raping a 60-year-old woman at knifepoint in his Illawarra home in 2012.
Had police at St George notified the parole board of the complaint, Sampieri's release could have been investigated and revoked, NSW Police Commissioner Mick Fuller told reporters in Sydney on Thursday.
But the parole board was not told of the alleged breach.
Sampieri went on to allegedly physically and sexually assaulted a seven-year-old girl in the toilet of a dance studio in Kogarah weeks later.
"At best an officer or the organisation potentially has failed to notify the parole board of a potential parole breach, and at worst an officer has neglected their duty to a victim of NSW," Mr Fuller told reporters in Sydney.
Prime Minister Scott Morrison said he was sure the NSW government was working to remedy the "abhorrent" event which, as a father, left him appalled.
NSW Premier Gladys Berejiklian apologised for the system's failure to intercept the alleged attacker.
"Getting it wrong may have resulted in the most terrible of circumstances and we are deeply, deeply sorry to everybody affected," she told parliament on Thursday.
NSW Police Minister Troy Grant said the whole discussion made him "crook in the guts" but the investigation had to run its course and the welfare of victims needed to be of paramount concern.
"The answers will come and, rightly so, everyone will get to know that and a full explanation will be forthcoming but lets all please respect those victims," he said.
He refuted long-standing claims made by the police union that high-risk sex offenders could slip through the cracks of an overworked and under-resourced force.
NSW Labor leader Michael Daley said the government's decision to mount the blame on one officer revealed the "fatal flaws" of the parole system.
"People want to know why (Sampieri) was not supervised, why he was not wearing an ankle tracker," he told reporters in Sydney.
"The system has failed and blaming a single officer is a cowardly response."
He called for a full public inquiry and pledged to establish one if elected.
Sampieri remains under guard in hospital and police are waiting for medical professionals to grant his release when he will likely be hit with fresh charges.
