Former homicide detective Paul Ferguson has put away his fair share of bad guys. The retired police officer was in charge of the MACRO Taskforce when it was created, after Jane Rimmer disappeared in June 1996, but before that, he worked on, and helped catch one of WA's most infamous serial killer couples - David and Catherine Birnie.

But the disappearances of Sarah Spiers, Jane Rimmer and Ciara Glennon was one of the cases that not only haunted WA, but many of the police officers who worked it.

The retired detective even interviewed the man he put behind bars, David Birnie, to try and get an insight into the mind of a serial killer.

He investigated when Sarah Spiers went missing. From the start, it was clear it wasn't just another missing woman. The Spiers family and police were onto it straight away. More than 2,000 posters, 20,000 flyers and 50 buses with Sarah's face were distributed throughout Perth.

Police had no idea how she was abducted, or even where she was. The search spanned all over the Perth region, from Black Wall Reach, to Midland, to Serpentine Falls. Sarah had disappeared without a trace.

In this podcast, Paul Ferguson reveals where he thinks Sarah Spiers is.

Five months after the 18-year-old disappeared, he recalls the call he took, the call that police knew was coming, but were dreading. Another woman had gone missing.

"The fact that we didn't know how that Sarah had been abducted, the fact that there'd been no commotion and the fact that her body hadn't been found was of major concern through the inquiry team and WA Police.  And then of course the worst thing that could have happened was another girl go missing from the same area," he told the Claremont in Conversation podcast team.

He admitted the disappearance of Ciara Glennon was a blur, because the investigation had become so intense.

Join Natalie Bonjolo, Tim Clarke and special guests former head of MACRO Paul Ferguson and former WA Police Commissioner Karl O'Callaghan as they take you inside Australia's longest running and most expensive murder investigation.

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