The male victim met two men and a woman, who he did not know, in Northbridge at approximately 3.40am on Friday 16 December 2016.
They began walking along Roe Street towards McIvor Train Station when one of the men grabbed the victim from behind, throwing him to the ground and punching him to the face. The two men stomped on the man while he was on the ground causing severe facial injuries. The men and woman grabbed the victims backpack and ran from the scene.
The man was assisted by a member of the public and St John ambulance took the victim to hospital.
The first man is described as: Light skinned, medium build, dark, short hair, goatee beard, approximately 18-25 years of age. Wearing long, dark pants, dark shoes and a green/grey T-shirt with a logo. Tattoos visible on both forearms.
The second man is described as: Light skinned, medium build, dark hair possibly tied up at back, dark beard and moustache, approximately 25- 30 years of age. Wearing light blue jeans, black boots, long sleeve black jumper with white writing on front.
The woman is described as: Light skinned, thin build, long straight dark hair, approximately 18-25 years of age. Wearing a white sleeveless top, light blue jeans and white sneakers.
Police have released a CCTV image of a woman who they believe can assist them with their enquiries.
If you have any information about this offence make a report online at crimestopperswa.com.au or call Crime Stoppers on 1800 333 000, where all calls are strictly confidential, and rewards are offered. Please quote Reference Number 8362.