The lead prosecutor in the Claremont serial killings case has conceded she does not know what direction Bradley Edwards's defence lawyers plan to take in the marathon Supreme Court trial, describing their case as "a guessing game".
Edwards is standing trial in the WA Supreme Court over the deaths of Sarah Spiers, Jane Rimmer and Ciara Glennon who disappeared from Claremont in 1996 and 1997.
He denies the murder charges against him but has admitted to attacks on two other women, including the abduction and rape of a teenager at Karrakatta cemetery in 1995.
On Thursday former forensic scientist Carole Evans, who has travelled from the UK to appear at the trial, was asked more about the processes she went through to test a series of exhibits relating to Ms Rimmer and Ms Glennon.
In 2008 hair, nail and clothing samples were flown to the UK's Forensic Science Service laboratory where scientists performed an advanced technique called low copy number (LCN) testing.
The sensitive testing method is designed to detect traces of DNA on very small pieces of material and it was during these tests a male DNA profile later linked to Edwards was uncovered under Ms Glennon's fingernails, marking a major breakthrough in the long-running investigation.
The following year, the Forensic Science Service also conducted a series of tests on evidence relating to the Karrakatta case.
Defence remains guarded on strategy
Questions about those tests prompted an objection from Edwards's defence lawyer, Paul Yovich SC, who questioned the relevance of the information, given his client had already confessed to that crime.
Prosecutor Carmel Barbagallo SC told the court she was trying to cover all bases given she had no idea what direction the defence planned to take.
"I don't know what the defence is quite frankly," Ms Barbagallo said.
"I don't know where they are going with the DNA.
"It may be that this has no role to play, but it may be that it does.
"Quite frankly, it's a guessing game."
During his brief opening address, Mr Yovich gave little away about the defence's argument.
At the time, he conceded the DNA found under Ms Glennon's fingernails, which was catalogued as exhibits AJM 40 and 42, belonged to Edwards but said he would argue it got there by way of contamination.
He has since been attempting to identify opportunities for that to have occurred.
"The defence accepts that the mixed DNA profile extracted from the sample that became AJM40 and 42 is consistent with a two-person profile, the contributors of which are Ms Glennon and the accused," Mr Yovich said back in November.
On Thursday Justice Stephen Hall asked him to clarify whether that was still his position, but Mr Yovich was vague in his response.
"Whether it is or isn't, results relating to intimate results on [the Karrakatta victim] don't go to prove anything other than those results," Mr Yovich said.
Later, Ms Evans was asked about mitochondrial DNA testing performed on samples of hair taken from Ms Glennon's underwear and from two drop sheets that were used during her post-mortem examination in 1997.
She concluded that the hairs had likely come from Ms Glennon and nine other individual sources.
However, none of them came from Edwards.
The trial continues.
