The disappearance of three young women, and the discovery of two of their bodies in the late 1990s, paralysed Perth with fear and sparked Australia's longest-running and most expensive police investigation.

Despite a dedicated police taskforce being set up and massive resources thrown at the case, including the offer of a $250,000 reward, the murders have remained unsolved for two decades.

The three women disappeared from upmarket Claremont in Perth's leafy western suburbs between January 1996 and March 1997.

Sarah Spiers was the first victim of the Claremont serial killer, but her body has not been found. ( ABC News )

The youngest, 18-year-old secretary Sarah Spiers, was enjoying a night out at the trendy Club Bayview nightclub in the centre of Claremont in January 1996.

After hailing a taxi, she disappeared and her body has never been found.

Childcare worker Jane Rimmer, 23, was the next to go missing on June 9 the same year.

Ms Rimmer had also been in Claremont with friends on a night out, drinking at the Continental Hotel. When her friends offered to share a taxi home, she declined.

It was the last time she was seen alive.

Jane Rimmer's body was found in bush in Perth's southern suburbs. ( ABC )

Lawyer Ciara Glennon was the last of the three to disappear in March 1997, again from Claremont.

By this time the body of Ms Rimmer had been found in Wellard, south of Perth, and police had established the Macro Taskforce.

Ms Glennon had also been drinking at the Continental Hotel.

She was last seen on nearby Stirling Highway, having left the venue around midnight on March 15.

Ms Glennon's body was discovered in bushland at Eglington in Perth's north in April 1997.

There have been more than 10 independent reviews of the Claremont investigation by expert crime fighters from other states and around the world.

Police made numerous public appeals for information and for years monitored one suspect 24 hours a day, seven days a week.

Like the killer's other two victims, Ciara Glennon had been on a night out in Claremont. ( ABC News )

The man, a public servant, denied having anything to do with the serial killings and he was eventually told he was no longer a person of interest.

In 2008, police came under heavy criticism when they released never-before-seen CCTV footage of Ms Rimmer just before her disappearance.

It showed her standing outside the Continental Hotel about midnight on June 9, 1996, when a man approaches her.

Police said the man was the only one in the footage they had not been able to identify, but as far as is publicly known, he has never been found.

There was another breakthrough last year when reports emerged that new DNA technology had established a link between Ms Glennon's murder and the man who raped a teenager in Karrakata two years earlier.

Police would not confirm the reports and at the time said they would not be commenting because they did not want to jeopardise any future prosecutions.