Two women have told the Claremont serial killings trial they saw a woman matching Ciara Glennon's description leaning into a vehicle on a Perth highway on the night she vanished.

Former Telstra technician Bradley Robert Edwards, 51, maintains he did not murder the 27-year-old solicitor in March 1997, and 18-year-old secretary Sarah Spiers and 23-year-old childcare worker Jane Rimmer in 1996.

Several people saw Ms Glennon walking alone down Stirling Highway on the night she went missing, minutes after she left colleagues at the Continental Hotel.

Lawyer Ciara Glennon's body was discovered in bushland weeks after she disappeared. (Supplied)

Susan Robinson testified on Monday that something made her look twice as she and her husband drove past, saying she saw a slight-built woman leaning towards a light coloured vehicle "talking to somebody".

"I'm certain that he had light brown hair," she told the Western Australia Supreme Court.

"In my mind at the time, I thought he was quite handsome."

Ms Robinson provided a description of the man for a police sketch artist the following month.

This never-before-seen face of a mystery driver, caught creeping on a young woman the night after Sarah Spiers disappeared, has been shown in the Claremont serial killings trial. (Supplied)

Lisa Mighall said she glanced at a slim woman standing next to a light coloured vehicle, which may have been a station wagon or ute similar to a Commodore, bending over like she was getting in.

That model has been referred to several times by other witnesses.

"It was definitely between midnight and 12.30am," she said in her statement.

The Claremont killings victims: Sarah Spiers, Ciara Glennon and Jane Rimmer. (Graphic: Tara Blancato)

Margaret Rogers said she saw a woman who looked like Ms Glennon in her headlights.

"She was ambling along and appeared to be relaxed," Ms Rogers said in a statement.

She also saw a tall man with dark hair walking behind the woman, but she did not think they were together.

She described the woman as being aged in her mid-20s and just over 150cm tall, while other witnesses including Patricia Mullan reported seeing a smartly dressed female.

Ann Kennerly said the woman was "a little unsteady" on her feet and may have been intoxicated.

A woman who dated the accused Claremont serial killer will give evidence at his trial that they visited a "heritage looking pub" in the area and repeatedly spoke about her safety after women vanished. (Supplied)

But Angela Rainbow testified she believed she saw Ms Glennon walking in a straight line, not swaying.

"She looked like she was on a mission," she said.

Lynette Steenholdt was also adamant who she saw.

"I saw Ciara Glennon. It was about 12.20am," she said.

"She was holding up her bag ... she was trying to get a taxi."

The Toyota Camry station wagon Bradley Edwards drove around the time of the Claremont murders (Supplied)

Thai restaurant cook Phetchara Mombao said she had just closed the venue when her colleague commented on the lone woman's appearance, saying "she may be the next to go".

The court has previously heard three men known collectively as "the burger boys" because they were eating outside Hungry Jacks shouted out the woman they saw was "crazy" for hitchhiking.

Ms Glennon and Ms Rimmer's bodies were found in bushland at opposite ends of Perth, but Ms Spiers has never been found.