A man remains in an induced coma after an assault that left him unconscious along Mandurah Road on Christmas Day.
On December 25, the man was found laying in the northbound lane, between Pinjarra Road and Leslie Street.
Detectives will allege the assault occurred between 6.40pm and 7.10pm.
The man required medical treatment and was taken to hospital by St John Ambulance.
Police are appealing to witnesses and anyone who may have been in the area at the time with vehicle dash-camera or mobile phone footage.
If you have any information that can assist, please contact Mandurah Detectives Office on 9531 8888 or Crime-Stoppers on 1800 333 000.