A drug-affected man who murdered a woman by deliberately driving on the wrong side of a West Australian highway and crashing into her car has apologised but says he has no memory of what happened.
Shaun Southern steered onto the wrong side of Bussell Highway in February last year, killing 61-year-old Jennifer Pratt and seriously injuring her passenger Karen Williams.
The WA Supreme Court heard on Thursday that Southern had no memory of what happened.
"I cannot believe I did what they say I did. It's awful," he said in a report referenced in court.
Defence counsel Justine Fisher said her client was remorseful and had previously been of good character.
"He is very sorry for what has taken place and has no real explanation for it and can't offer the community any comfort," she said.
But prosecutor Justin Whalley pointed out it was not an accident and the reality was Southern would spend a lengthy period behind bars.
Southern had methylamphetamine and amphetamine in his system when he sped towards several cars, forcing them to swerve, before striking Ms Pratt's vehicle head-on.
Both cars had been driving close to the 110 km/h speed limit before the collision, but Ms Pratt hit the brakes and was travelling at 38 km/h at the point of impact, while Southern was driving at 86 km/h.
Southern was flung out of his car through the windscreen and was unconscious for some time, while his car also caught fire.
He was found guilty of murder and attempting to unlawfully kill Ms Williams.
Justice Michael Corboy acknowledged the three people who followed Southern and filmed his erratic driving.
"It seems to me their common sense and their attempt to intervene is particularly commendable."
Justice Corboy said he needed more time to consider the submissions before he could sentence Southern.
"I do understand that the completion of a sentencing process is a very important step in getting closure, so I am sorry that I'm not in a position to sentence today," he told the victim's family.
Southern will be sentenced on August 24.