A social worker who was attacked from behind by the accused Claremont serial killer has told a court she thought she was going to die.
Confessed rapist Bradley Robert Edwards, 50, is on trial in the Western Australia Supreme Court, charged with murdering Sarah Spiers, 18, Jane Rimmer, 23, and Ciara Glennon, 27, in 1996 and 1997.
The attack victim, whose identity is suppressed, testified on Tuesday she was distressed at having to relive what happened to her at Hollywood Hospital in 1990, which started innocuously when the former Telstra technician asked to use the toilet.
She admitted she "grunted" her permission because she was rushing to finish a report so she could go home for her daughter's birthday.
After she heard the toilet flush "a bit quick", Edwards emerged then said he had forgotten his pen and asked if he could retrieve it.
She thought it was a strange question but told him he could get it.
He instead he attacked her from behind.
"His hand came around my face. I was trying desperately not to breathe because I thought there was something on the cloth," she said.
"I honestly thought I was going to die.
"I breathed in and there was nothing on the cloth so that was when I started to really struggle.
"I thought 'I've got a chance here'.
"My feet kept slipping on the carpet. There was a lot of strength but I managed to twist around."
She said she was being "pulled back and hoicked up" towards the toilet.
The woman's chair fell over during the 10-second ordeal, which suddenly stopped.
"It was the strangest.
"One minute I was, I felt, fighting for my life and the next minute he's just saying 'I'm sorry, I'm sorry, I'm sorry'."
The woman said she got out of the room as fast as she could, wearing just one shoe.
Edwards swiftly admitted the attack, was sentenced to two years probation and ordered to compete a sex offenders program.
Clinical psychologist Paul McEvoy examined Edwards after the offence and reported he appeared to be "in a state of some distress" as his de facto had recently confessed she had been unfaithful to him early in their relationship.
He told her he accepted it but "was actually deeply distressed by her admission".
"Mr Edwards is unable to clearly identify why his pent-up anger should be released when it did, or why he acted it out on his victim, a woman whom he had only met that day," Mr McEvoy said in his report, which he read out in court.
"He acknowledges feeling angry that 'nothing was going right for me', but suggested that he was not angry with his victim."
Another psychologist, Lyn Millett, said Edwards "realised what was happening" when the woman screamed.
Edwards has since admitted five offences including rape.