Battling his own demons and struggling to come to grips with the realisation he was trapped in a cell thousands of kilometres from home, the Dutch national wanted nothing to do with the “sick puppy” and his evil ramblings.

But it was one of Guider’s stories that would help crack one of the most high profile missing persons cases in NSW history — the disappearance of Bondi schoolgirl Samantha Knight.

Previously known only as Witness O, the Daily Telegraph can now reveal that Frank Soonius, from Holland, was the prisoner who Guider confided in over his role in the death of nine-year-old Samantha.

Snatched from the streets near her Bondi home on August 19, 1986, Samantha’s disappearance and the mass search for her both captivated and terrified a nation.

Soonius was serving more than 10 years in Lithgow Jail in the 1990s for drug trafficking, having been caught when entering the country several years earlier, a crime he continues to deny.

Depressed and suicidal, Soonius had been placed in the protective wing for his own safety, while Guider was there to keep him away from other inmates who dished out prison justice to those who preyed on kids.

Guider would often talk about the young girls he had abused, but Soonius would block him out, not wanting to hear the boastings of a sick man.

“When I was in prison in 1998, I was so sick and all the things he was telling me I was always telling him to shut up,” Soonius told The Daily Telegraph from his home in the Netherlands.

“That’s why I never noticed he was telling me about more crimes and other things he had done.”

Soonius, now 58, then joined a prison bible group and when Guider asked if he could join, the foreign national and Christian took him along.

“He really became interested in some parts of the bible I was reading about,” Soonius said.

After the classes, Guider began to become concerned with the horrible things he had done in the past and what that meant for his future and beyond.

“He said ‘Look Frank you will be forgiven when you walk away from here but I will always burn,” Soonius said, recounting one of their conversations.

“But I told him: ‘No, Michael because if you come clean and you do your 16 years in jail for the things you have done then you’ve also got a chance to start again.”

Soonius had no idea his fellow prisoner was involved in the death of Samantha Knight and thought Guider feeling remorse for the abuse he had inflicted on the children that led to his conviction.

But after some time, Guider came to him again and dropped the bombshell that would partly solve a mystery that had haunted the city for years.

“He said ‘I gave her something in the cola and some sleeping tablets and during what I was doing to her she became a little bit awake so I gave her another cola with a tablet in it and I went shopping,” Soonius recounted.

Guider continued to tell him: “Most of the time they wake up (but) when I came home I went to the couch and she was cold. She was dead.”

Samantha Knight’s body has never been found, but Soonius said Guider had told him in prison what he’d done with her remains after her death.

Two years after the she vanished another young girl is believed to have gone missing in the area. Not much is known about that case, but Soonius said Guider told him he was spooked by the police search and moved Samantha’s body from where he had buried it in Bondi.

“He was scared and before even the search started (for the second girl) he dug her up and put her in a container and made sure she went into where they burn all the garbage,” he said.

“Then he took her remains and made them so small and put them under all the garbage from the garden job he did and dumped it where the garbage goes.”

After he was charged with her murder — which would later be downgraded to manslaughter in a plea agreement — Guider told investigators he didn’t remember where he had buried Samantha.

But Soonius believes the killer was telling the truth when he recounted what he had done with her remains.

“That day for the first time I thought he was open and I thought he was telling the truth,” he said.

Soonius was released in August 2000 after giving investigators the evidence that would help be charged with murder and convince him to eventually plead guilty to manslaughter.

On returning to The Netherlands, he began the process of piecing back together his life, opening a tennis school and starting to write a book about his extraordinary time in Australia.

He also started the process of clearing his name of a crime he said he never committed - a fight he promises he will never give up on.

Instead of having to deal with the frantic pace of the city, Soonius bought a cabin in the woods outside of Amsterdam.

Coming to Australia was one of the worst decisions the Dutchman has made in his life, but he is comforted by the fact he was able to help close one of Sydney’s most horrible chapters.

When told of the possibility the killer could be released as early as February next year, Soonius said the thought terrified him.

 “I’m scared, I’m really scared,” he said, obviously shaken at the prospect.

‘If you look into those eyes, they’re so horrible.’

“That scares the hell out of me. I hope they keep him under surveillance for 24 hours a day because he’s a really sick puppy, he really is.”

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