The man, who can only be identified by the pseudonym SLD, was aged 13 when he abducted the sleeping girl from her Central Coast bed before he placed her on a concrete driveway and stabbed her in the heart with a steak knife.

He dumped her body up an embankment before going home, changing his clothes and washing his hands.

Justice James Wood described the killing as "disturbing", "motiveless", and a "parents worst nightmare" when he sentenced SLD to 20 years behind bars with a non-parole period of 10 years.

His earliest possible release date was January 2011, dependant on his rehabilitation progress.

When SLD had served his 20 years, the state applied to the Supreme Court for a continuing detention order, a mechanism to detain prisoners who are an unacceptable risk.

Wollongong Local Court heard during SLD's bail application on Wednesday that he had only recently been released.

The now 36-year-old, of Campbelltown, was deemed a high-risk violent offender by the NSW Supreme Court in April.

He was subsequently placed on an extended supervision order with 66 conditions that aim to reduce his risk of offending.

Police will allege SLD approached three women and their children at Bulli Beach on Tuesday, October 24, in defiance of his condition banning him from associating with anyone under 18.

Tendered court documents state he was at the beach shortly before midday with a support worker when an off-duty community corrections officer noticed him wearing a GPS ankle montior.

SLD allegedly spoke to a woman on the beach before she picked up her child and walked away.

Police will allege he then spoke to another woman who was washing her infant in the public shower area, before she grabbed her child and left.

SLD allegedly made a third attempt to engage with a woman, who was feeding her child at a nearby cafe, saying to her: "I just got out of jail ... do you come here often?"

"Yes, I like this beach," the woman allegedly replied, feeling uneasy.

The off-duty officer then approached SLD and said: "I have watched you approach and speak to three separate women ... I'm calling the police."

Police arrived shortly after and arrested SLD. In arguing for his release, defence lawyer Matt Kwan said SLD wasn't interacting with the children and that it had only been "incidental contact".

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Mr Kwan submitted SLD cooperated with officers as he believed he had done nothing wrong, adding there were "severe evidential holes" in the police case.

However Magistrate Darryl Pearce said SLD must have been aware there were children at the beach, and was of the view the condition had been breached.

"He put to (the women) he had come from jail, why would be tell them that?" the magistrate posited.

Magistrate Pearce refused SLD bail which elicited a colourful response.

"This is bulls---, I'm gonna sue you dog," SLD said. "If I get bashed in here youse are all f---ed."

The matter will return to court in December.