Scientists matched fibres taken from the hair of two murdered women to a model of car driven by their alleged killer three years before he was arrested, the WA Supreme Court has been told.

Key points: Bradley Robert Edwards is on trial for the murders of three Perth women

Bradley Robert Edwards is on trial for the murders of three Perth women Perth's ChemCentre has examined more than 10,000 fibres in the case

Perth's ChemCentre has examined more than 10,000 fibres in the case Fibres from the type of pants Edwards wore match 44 found on one victim

Forensic chemist Rees Powell, who works at the state's chemistry laboratory ChemCentre, was testifying at the triple murder trial of former Telstra technician Bradley Robert Edwards.

Edwards, 51, is accused of the wilful murders of 18-year-old Sarah Spiers, 23-year-old Jane Rimmer and 27-year-old Ciara Glennon.

The women went missing from Claremont, in Perth's western suburbs, late at night in 1996 and 1997. Only the bodies of Ms Rimmer and Ms Glennon have ever been found.

Dedicated database for vast fibre collection

Mr Powell, who has worked on the Claremont case since 2011, described the laborious and detailed process he and his colleagues undertook to retrieve and analyse thousands of fibres related to the case over a number of years.

He told the court the volume of fibres collected in relation to the case was so overwhelming, a special database had to be developed to handle such large quantities.

That database has since gone on to become one of only two in the world specialising in fibre matching, and a key tool in solving crimes around Australia.

Mr Powell said in total more than 10,000 fibres were collected relating to the case.

These included nearly 4,500 fibres from the bodies of Ms Rimmer and Ms Glennon and the surrounding bushland areas where they were found, and from the vegetation used to cover their bodies.

Other fibres examined included those taken from the clothing worn by a 17-year-old girl who was brutally raped by Edwards at Karrakatta Cemetery in 1995, and fibres taken from vehicles of interest in the case.

A ChemCentre worker cutting fibres of interest from a sample in the lab in 2017 (file image). ( ABC News: Rebecca Turner )

Mr Powell told the court by 2014, ChemCentre scientists working on the case had analysed and grouped together fibres that shared similar qualities, but because there was no person of interest at that time, they had nothing to compare them with.

Instead, they tried to find a match for the fibres that had appeared to have come from a vehicle or vehicles by scouring car dealers and wreckers' yards.

Crucial car match

They discovered 20 grey polyester fibres found in Ms Rimmer's hair matched the seat insert fabric used in 1996 VS Holden Commodores.

Edwards drove a Telstra-issued 1996 VS Holden Commodore between April 1996 and late 1998, during the time Ms Rimmer and Ms Glennon were murdered.

Mr Powell said a further fibre found in Ms Rimmer's hair matched the fibre used in the carpet at the rear of the 1996 VS Commodore.

In December 2016 Edwards was arrested and on the same day, police tracked down his Holden Commodore and seized it from its owner in Chidlow.

Scientists were now able to compare fibres from the car he actually drove to those found on the victims, Mr Powell said, and these were also found to be a match.

For example, three fibres found in Ms Glennon's hair matched the seat insert of the Commodore, while seven fibres also found in her hair matched the carpet in the cabin area.

Accused serial killer Bradley Edwards' Telstra car was seized by police from a man he sold it to. ( Supplied: WA Supreme Court )

Work trousers match fibres on bodies

Fibres found on Ms Rimmer, Ms Glennon and the teenage girl Edwards raped were also matched to samples of Telstra-issued work trousers of a type that the former technician wore at the time.

Scientists used a sample of the trousers, which the court previously heard were manufactured by Yakka from polyester and rayon in a unique colour called Telstra navy, donated by a former Telstra worker who was also working for Telstra in the mid 1990s.

A total of 60 blue polyester fibres were found matching the type of trousers Edwards wore — 44 from Ms Glennon's hair and shirt, 13 from the car he drove, two from the 17-year-old girl's shorts and one from Ms Rimmer's hair.

Samples of Telstra-issued work trousers of a type Bradley Edwards wore at the time were examined by ChemCentre. ( Supplied: Supreme Court of Western Australia )

"I would consider them to have corresponding properties," Mr Powell said.

The trial, before Justice Stephen Hall, is continuing.