The Claremont serial killings trial has been delayed for at least two days after the discovery of 400 pages of new material relating to the detection of male DNA under the fingernails of victim Ciara Glennon.

Key points: DNA collected from Ciara Glennon's nails was examined by PathWest

DNA collected from Ciara Glennon's nails was examined by PathWest They have now revealed 400 new pages of DNA-related documents

They have now revealed 400 new pages of DNA-related documents This evidence is deemed crucial to the case against Bradley Edwards

Bradley Edwards is on trial in the WA Supreme Court for the wilful murders of Sarah Spiers, 18, Jane Rimmer, 23 and Ms Glennon, 27, in 1996 and 1997.

Tiny fragments of Edwards's DNA found under the fingernails of Ms Glennon are considered crucial to the prosecution's case.

Forensic scientists from PathWest, the state's pathology laboratory, have been giving evidence about examination techniques and record keeping regarding these pieces of evidence.

Today the court was told that on the weekend PathWest found about 400 pages of material in three separate files that had not previously been disclosed at the trial.

The material had been scanned by the state pathology laboratory, but had not made it onto the disclosure spreadsheet.

Justice Stephen Hall, who is presiding over the marathon judge-alone trial, described the situation as "extremely unsatisfactory".

Bradley Robert Edwards was arrested in 2016 after a crucial DNA discovery. ( Supplied: Supreme Court of WA )

PathWest urged to explain 'disclosure issue'

State prosecutor Carmel Barbagallo SC said the new material related to the work undertaken by PathWest scientist Alexsander Bagdonovicius on Ms Glennon's fingernail samples.

Mr Bagdonovicius began giving evidence last Thursday, telling the court PathWest had conducted a specialised DNA test called Low Copy Number testing (LCN) on some of the fingernail samples, even though it was not accredited to do those tests.

He said these LCN results found trace DNA on AJM46 — Ms Glennon's right index fingernail, an exhibit critical to the prosecution case — and the result was passed onto detectives, but the results were not reportable in a court of law because of the lack of accreditation.

State prosecutor Carmel Barbagallo SC revealed details in court about the new material. ( ABC News: Carmel Barbagallo )

Ms Barbagallo said the new material related to how Mr Bagdonovicius handled the exhibits in July and August 2003, and how he recorded and analysed the test information on a matrix.

Defence counsel Paul Yovich SC said while he agreed with Justice Hall that the late disclosure was unsatisfactory, he was keen that the new material be carefully examined, suggesting that the delay could be longer than two days.

"I am conscious of the need for this trial to stay on the rails, but we should not compromise proper full disclosure of material on such a crucial issue for the sake of one day less," he said.

He also said PathWest needed to explain in a statement how the material came to be overlooked, to which Justice Hall concurred.

"Frankly I would like to see some statement that explains how this disclosure issue has arisen," Justice Hall said.

Boost to defence DNA argument

While it is not yet known how important the previously undisclosed material is, the error has boosted the defence's case that PathWest did not follow appropriate processes and procedures in dealing with crucial evidence.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 59 seconds 3 m 59 s A timeline of the Claremont serial killings

A batch of Ms Glennon's fingernail samples was eventually sent to the UK in 2008 for further LCN testing, where scientists at a Forensic Science Service laboratory made the breakthrough discovery of male DNA after combining AJM 40 and 42.

It was not until 2016 that the DNA was matched to Edwards and he was arrested shortly afterwards.

The trial is scheduled to resume on Wednesday, when Mr Bagdonovicius is due to continue his evidence.