Serial paedophile Michael Guider will be released from prison on a five-year supervision order of "great stringency", a NSW judge has ruled.

Key points: Michael Guider drugged and killed nine-year-old Samantha Knight in 1986

Michael Guider drugged and killed nine-year-old Samantha Knight in 1986 He has never revealed what happened to her body

He has never revealed what happened to her body He will be subject to 55 strict supervision conditions which aim to protect the community

Guider's 17-year jail sentence expired in June after he pleaded guilty in 2002 to the manslaughter of nine-year-old Samantha Knight.

The schoolgirl was kidnapped from Bondi, drugged and killed in 1986, but Guider has never revealed her final resting place.

The NSW Attorney-General applied to keep him in custody for at least another year, but Guider's lawyer argued 55 strict supervision conditions would protect the community.

Justice Richard Button said he had imposed a five-year extended supervision order of "great stringency".

The court found although there was some risk in releasing Guider, further incarceration would not serve any rehabilitative purpose.

Justice Button said the law called on him to weigh up whether there was an "unacceptable risk that could only be forestalled by further incarceration", rather than any risk.

"The fact is, that there is some risk in releasing any person on the complete expiry of his or her sentence who has been shown to commit offences of the utmost gravity in the past, whatever their particular nature," he wrote in his judgment.

Guider's current detention order expires on September 5.

Last month, Samantha's mother Tess Knight begged the court to keep Guider locked up and said she had constantly played out her daughter's final moments in her mind.

Tess Knight said she believed Guider was still a danger to the community. ( ABC News )

Psychiatrist Jonathon Adams said Guider accepted "criminal responsibility" for his actions but did not comprehend the moral wrongfulness of his offence.

Dr Adams said Guider posed a high risk of future sexual reoffending but Justice Button said the defendant had done all that can be done in terms of rehabilitation in a prison setting.

The court was told he was willing to take anti-libidinal medication.

His lawyer, Matthew Johnston SC, said Guider had engaged in rehabilitation and already had limited exposure to the community, including wearing an ankle bracelet.

Guider abused 13 other boys and girls and one of those victims, Lisa Giles, told the court Guider took pleasure in robbing children of their innocence.

"He's not finished yet," she warned.