A 21-year-old woman is warning the community to be careful after she was sexually and physically assaulted on the Mandurah eastern foreshore in an "unprovoked attack".
Shenae Peebles said she was was lying on the grass waiting for an Uber with a male friend, between the playground and toilet cubicle, about 2am, on October 19, after a night out in town.
The childcare worker said an unknown offender came up from behind before kicking her friend in the head "like a soccer ball".
"It knocked him out straight away," she said.
"My head was next to his, so it impacted onto my head. All I remember is screaming at the top of my lungs."
Ms Peebles said the offender smothered her face before indecently assaulting her.
He tried to undo her belt but when he failed, Ms Peebles said he threw her against a concrete picnic table.
"I woke up with a bruise on my chest and a big scratch on my face," she said.
"I was in complete shock, screaming and beside myself.
"I kept having horrible flashbacks the next day. It was so unprovoked."
Ms Peebles said she wanted the man to "pay for what he did".
"It would put my mind at ease and help me put it in the past," she said.
"I also want people to be aware of this and know he hasn't been caught."
Mandurah Detective Senior Sergeant Trevor Troy said the incident was closed, pending new evidence.
"This was a random attack," he said.
"It's a rare incident and we don't know why it occurred.
"We have spoken with three witnesses, but have not received any reliable information."
Senior Sergeant Troy said the incident occurred in a CCTV "blind spot" and the forensic results have not produced any substantial DNA evidence.
Senior Sergeant Troy encouraged people to be "mindful" if they were out late at night.
"We have seen very few incidents around the CBD with the success of Operation Sky Kite," he said.
"But as always, it is important to be mindful of your surroundings."
Operation Sky Kite is a police operation targeting anti-social behaviour in the Mandurah CBD, which includes increased foot patrols in the day and night.
If you have information that could help police contact Crime Stoppers on 1800 333 000.
For free sexual support counselling contact Allambee Counselling at the Peel Health Hub on 9535 8263.