In 1986, 9yo Bondi girl Samantha Knight was murdered. This week her killer will walk free.

The photograph ran on the front page of Sydney’s The Daily Telegraph in August, 1986. A nine-year-old girl, wide green eyes peering out from beneath a large yellow cap. The image anchored a story that sent the city into a frenzy that winter, that of the disappearance of Bondi schoolgirl Samantha Knight.

Samantha had vanished from the beach-side suburb on August 19. But it would be almost 15 years before police found answers.

In February 2001, convicted paedophile Michael Guider confessed to drugging, sexually assaulting and accidentally killing the little girl. When sentenced for manslaughter over Samantha’s death, he was already serving time for 60 sex abuse charges relating to the molestation of multiple children between 1980 and 1996.

This week, though, Michael Guider will walk free.

Listen: The journalist who broke the Samantha Knight story shares his memories of the early days of the case.

On Tuesday morning, a judge rejected an application from the NSW Attorney General to keep the now-68-year-old behind bars for another year beyond the expiration of his 17-year prison term. Justice Richard Button instead imposed a five-year extended supervision order with stringent conditions, including electronic monitoring.

In delivering the decision, the judge noted that while it could not be definitively determined that Guider’s sexual interest in children had disappeared, further imprisonment wouldn’t serve any rehabilitative purpose.

Samantha Knight’s disappearance.

Samantha’s mother, Tess Knight, had come home from work on the afternoon of August 19, 1986, to find the remnants of a snack Samantha had made herself sitting abandoned on their kitchen bench. Tess presumed her daughter was out playing in the streets of their laid-back suburb or at a friend’s house, as she often was after school. But as darkness arrived without the little girl’s return, it became clear something was wrong.

Journalist Mark Morri was among the lead reporters to break the story of Samantha’s disappearance. He still recalls the first time he saw the photograph of her in the yellow cap. It was sitting in the living room of Tess’s apartment, almost a week into the search.

"I remember going into the block of flats in Imperial Avenue and I remember Tess opening the door and just what struck me was the rings under her eyes. It looked like she hadn't slept for a week. It was really quite confronting," he told Mamamia's True Crime Conversations podcast.

"I can't remember a real lot about what she said. But I do remember we've got a photo album, and that's where you see that iconic photo. And I think the fact that [Samantha] looks so innocent, too - we ran it all over page one. That just sent Sydney even into more of a spin."

Posters were plastered across the state. Her image circulated by media around the country.

But Samantha Knight was never found.

Michael Guider's confession.

A renewed investigation into Samantha's disappearance in the early 2000s unearthed the name Michael Guider. He ultimately confessed under questioning to kidnapping Samantha Knight, drugging her with sleeping pills and sexually assaulting her. He claimed that he never intended to kill her, but that when she woke during the assault, he administered a second dose of sleeping pills that proved fatal.

It's still not known where he disposed of her remains.

Tess Knight, last month pleaded at a Supreme Court hearing for Guider to be kept behind bars, arguing that he has failed to take adequate responsibility for his crimes and had provided conflicting accounts to police.

She told the court that she's plagued by questions about her daughter's final moments.

"Did she struggle? Where did he take her? Was it a long drive?" she said, according to ABC. "I imagine all these things in detail."

Guider's current detention order expires on Thursday.

Once out in the community he will be subject to 56 conditions placed upon him by the judge, including that he must not approach or have contact with anyone under 18, other than incidental contact in a public place, unless he has written permission.

He is also not allowed to change his name or use any other name without the approval of his supervisor, nor can he significantly change his appearance.

With AAP.