Police are hunting a predator who threatened a female jogger with a syringe before sexually assaulting her in a public toilet on Monday afternoon.
The 22-year-old woman had just finished a run when she visited the amenities at Mills Park in Kenwick between 3pm and 3.30pm.
As she left a cubicle she was confronted by a man holding a syringe.
"The man threatened her with the syringe and sexually assaulted her before letting her leave the toilets," police said.
"The woman drove home and contacted police."
The sexual assault has prompted a reminder from police for people to be mindful of their surroundings.
The offender is dark-skinned, in his 20s, about 173cm tall with an athletic build and short dark-brown hair.
He was wearing a black silky long-sleeved top with a round neck, possibly Adidas, and a white cap and had a dark bag hanging over his shoulder to his waist.
Anyone with information about the incident should contact Crime Stoppers on 1800 333 000.