IT took Denise Hofman nearly two years to convince senior police that Michael Guider was one of Australia's most notorious child killers.
Now the mother-of-five says they are refusing to consider her concerns that Guider, who killed nine-year-old Samantha Knight, may have murdered other children.
Mrs Hofman, 58, has revealed that a set of scrapbooks once kept by Guider contain newspaper cuttings about the unsolved abduction and homicide of five-year-old Renee Aitken on the state's South Coast in 1984.
Other circumstantial details potentially link the 55-year-old pedophile to the disappearance, she said.
However, senior police insist that without more evidence they can't take the matter further.
None will allow Mrs Hofman access to the scrapbooks, which they say are filed in the force's investigative archives.
Nor are they willing to examine the exhibits or discuss their contents with her, she said.
Mrs Hofman, who learnt of the scrapbooks' existence through the Guider investigation, now wonders whether at least some of the clippings have been lost.
"I'm getting the same sort of responses from the police that I did when I was trying to tell them about Samantha," Mrs Hofman said.
"They're not answering the questions I'm putting to them. They're refusing to produce the scrapbooks and they're saying at a very high level that they don't even need to go and look at them for themselves."
Guider, 55, was sentenced to 12 years' jail in August 2002 for Samantha's manslaughter, thus closing the book on a 16-year mystery. He could be released as early as 2014.
But his conviction would never have happened without Mrs Hofman's determination to expose her former friend as a suspect and then go under cover to help prove his guilt.
Mrs Hofman and Guider met in 1993 via a mutual interest in Sydney's Aboriginal rock sites but three years later she was shocked to learn that Guider, who worked closely with the National Parks and Wildlife Service, was in jail awaiting trial over child sex allegations.
When a colleague confided to her that Guider had been obsessed with Samantha and helped search for her when she disappeared, Mrs Hofman decided to act.
Bondi police would not meet her, so she decided to visit Guider in prison and did so more than a dozen times before anyone would believe her story.
At one stage, she was told to walk away because Guider was simply not a suspect.
Mrs Hofman said Guider's police photograph was privately identified by a key witness in the Renee Aitken case.
She said a poem Guider sent her from jail also confirmed that he was working in the Canberra suburb of Red Hill, just two hours from Renee's Narooma home, around the time she was snatched.
A letter Mrs Hofman received from police two weeks ago said: "The [police] followed up the issues you raised in your representations and [are] satisfied that, unless further evidence is forthcoming, there are no additional avenues of investigation that can be legitimately pursued.
"I understand that you feel strongly about this issue; however, I must reiterate that, without further evidence, NSW Police is unable to take the matter further."
Former NSW Police consultant and serial crime authority Richard Basham said it was easy enough for police to question specifics "but the general issues being raised about this guy are more difficult to deal with because the police know what the actual chances are of him being a 'one-off' offender".
"Essentially any crime against a stranger needs to be regarded as part of a series until proven otherwise."
Dr Basham agreed that the mere fact Guider was already behind bars was not enough to dismiss whatever else he might have done.
"The parents [of other potential victims] certainly deserve better," he said.
Mrs Hofman believes the scrapbooks feature cuttings on other missing child cases as well.
While Guider's age would all but rule out any direct connection, she knows they include the 1966 disappearance of the three Beaumont children in Adelaide.
"Even tracking Michael's whereabouts over the past 20 years through the NSW National Parks and Wildlife registry would have to be be worthwhile, and very easily done," Mrs Hofman said.
"Wherever he was, the days, the dates, the sites, all of it, it's there in the register but it is something the police have never looked at."- Samantha Knight
walked out of her mother's Bondi flat on August 19, 1986, and never returned. For the next 16 years, her disappearance would be considered one of the nation's most baffling and disturbing crimes. A neighbour was the last person to see her alive when she waved to the pretty nine-year-old in Bondi Road. Samantha had earlier visited her nearby Imperial Avenue home to change out of her school clothes and fix something to eat. Knowing her mother was to return from an art class at 6pm, she then decided to walk down to a local pharmacy to buy a toothbrush.
- Michael Anthony Guider was 35 when he abducted Samantha in Bondi's Wellington Street. For the previous three years he had secretly drugged and abused her but it was not until 2002 that he confessed to her manslaughter, claiming to have accidentally given her a fatal overdose of the sedative Normison. Guider was already serving 16 years' jail following his conviction in 1996 for the sexual assault and drugging of 11 other children aged two to 16. Even so, he refused to talk about Samantha's death or say where he had left her body. Former prisoners told police Guider may have buried her in an eastern suburbs park before exhuming the remains and dumping them in a construction site bin.
- February 16 will mark 23 years since little Renee Aitken's bewildering disappearance and suspected murder. Exhaustive search efforts failed to find a trace of the five-year-old, snatched from her Narooma bedroom in 1984. Various sightings of her over time have all proved false, including an American woman's bizarre claim to being the adult Renee. A computer-generated likeness of what a 22-year-old Renee might look like, which was circulated in 2001, also failed to produce a lead. Hope of a breakthrough then emerged the following year, when police declared interest in a man previously convicted of assaulting one of Renee's relatives. However, he died in a car smash without being questioned, just weeks before Coroner Carl Milanovich returned an open finding at inquest.