Western Australia's police chief has vowed to never stop trying to find the body of Sarah Spiers after Bradley Robert Edwards was acquitted of her murder but convicted of killing two other women during a "decade of terror".
Edwards has been found guilty of abducting and killing childcare worker Jane Rimmer, 23, and solicitor Ciara Glennon, 27 in Perth in the 1990s but acquitted of slaying 18-year-old secretary Ms Spiers, whose body has never been found.
WA Supreme Court Justice Stephen Hall said he was satisfied Ms Spiers, who disappeared after a night out in Claremont in 1996, had also been abducted and killed.
Justice Hall said the evidence showing Edwards' propensity for violent abductions "makes it more likely" that Edwards was the killer of Ms Spiers.
But he said it could not be proved beyond reasonable doubt in the absence of any other evidence about the killer's identity.
It leaves more unanswered questions for Ms Spiers' parents Don and Carol, who left the court in silence.
Police Commissioner Chris Dawson, who described Edwards as "an evil murderer and rapist", said the investigation into Ms Spiers' death remained open.
Detectives plan to interview Edwards again in the hopes he will disclose anything he might know.
"We will never give up trying to locate Sarah, and I have conveyed that to Don and Carol Spiers today and to (her sister) Amanda," Mr Dawson said outside court.
"Sarah and her family deserve justice."
Premier Mark McGowan urged Edwards to reveal whether he has any knowledge of where Ms Spiers' body is located.
"If you know where Sarah Spiers is, can you please tell us," he said.
"Please tell the family. Let them bury their daughter."
Mr Dawson acknowledged the work of his detectives and the prosecution team led by Carmel Barbagallo for their role in bringing Edwards to justice.
"Bradley Edwards' crimes spanned a decade of terror starting with violent assaults that escalated to the murder of young women," he said.
Earlier, Jane Rimmer's sister Lee praised investigators and said she was pleased about the two guilty verdicts.
"It means that I can hopefully get on with the rest of my life without all this stuff," she said.
She said the acquittal was very sad for Ms Spiers' family.
"Everyone just gave each other a hug when we were inside," she said.
"It's very sad but (we're) glad that we got the result for the other two."
Ms Glennon's family, including her father Denis Glennon, also left the court in silence.
The police murder investigation was the longest-running in the country, dealing with almost 18,000 suspects including those who had to be screened for DNA testing and individuals directly nominated by members of the public.
Edwards' seven-month trial was Australia's most expensive at more than $11 million.
He will return to court for sentencing submissions in December.
Australian Associated Press