Police need help identifying a man believed to have witnessed a serious assault on an 18-year-old man in central Perth earlier this month.
The victim was walking along William Street and then along Murray Street, toward Queen Street, with the man in the early hours of September 8.
Security footage shows the victim and the man laughing and talking.
Some time between 12.45 and 1.30am, the victim may have been assaulted by an unknown person.
The victim called for help at the intersection of Queen and Wellington streets.
He suffered serious injuries to his jaw and needed surgery.
Police are searching for the man pictured because the victim cannot fully recollect the night's events.
Anyone who recognises the man or has information on the incident is asked to contact Crime Stoppers on 1800 333 000.