Justice Richard Button on Tuesday rejected an application to keep Michael Guider behind bars for another year, instead imposing a five-year "stringent" extended supervision order with 56 conditions.

The now 68-year-old pleaded guilty in 2002 to the manslaughter of nine-year-old Samantha, who disappeared from Bondi on August 19, 1986. Her body has never been found.

Guider's 17-year jail term has expired but he was placed on an interim detention order that expires on Thursday.

Outside the NSW Supreme Court on Tuesday, Samantha's mother said she was angry at the decision, while one of Guider's many child-abuse victims said, "Hold your children close."

"A child molester and a child killer will be released among us this week," Lisa Giles told reporters.

"It's not over and we can see the inadequacies of the justice system very clearly today.

"He will reoffend and, when he does, those people who enabled this will be held accountable."

Tess Knight said she took some consolation from the fact Guider would be strictly supervised for five years but she was shaking inside at the prospect of his release.

"I see the effect that this has had on the people he abused as children, who are now young adults," she said.

"They have to live with the thought of him walking around having the freedom they don't have."

NSW Attorney-General Mark Speakman applied for the one-year detention order.

He's now seeking urgent advice on the prospects of appealing the decision and whether Guider can be kept in jail while an appeal is heard.

The 56 "extremely restrictive" conditions include electronic monitoring.

Guider must live in a halfway house attached to a prison and provide a weekly schedule of his movements three days in advance.

He can't approach or have contact with children nor visit certain places, including cinemas, libraries, museums, pools and sporting facilities, without the prior approval of his supervisor.

He can't consume alcohol or illegal drugs, change his name or appearance, attend premises providing sexual services or entertainment, and he must take anti-libidinal medication.

When sentenced for Samantha's death, Guider was already serving time for numerous sex offences against more than a dozen other children between 1980 and 1996.

Justice Button said he was required to assess the risk Guider posed in the future, rather than impose punishment for his prior offending.

"I do not accept that a further period of incarceration for 12 months would serve any rehabilitative purpose," he said.

Three experts, highly experienced in psychology and psychiatry, agreed Guider's risk could be reasonably managed under a stringent and lengthy system of supervision within the community.

"The defendant has been incarcerated for a continuous period of over 23 years," the judge said.

"He has done all that can be done in that setting to further his rehabilitation with regard to his undoubted sexual attraction to children."

The most optimistic thesis about his sexual drive was a gradual reduction over the years in such an attraction as part of an ageing process and as a result of "sincere engagement in therapy".

The judge said the law required him to reflect on whether the attorney-general had established "an unacceptable risk" - not any risk - that could only be forestalled by further incarceration.

Mr Speakman had not sought an incarceration order for more than 12 months and envisaged Guider being highly restricted after that.

That raised a "question of futility" with regard to further incarceration, Justice Button said.

Australian Associated Press