UPDATE 12:56pm Members of the State Emergency Service have arrived in Fremantle to assist police in the search for a potential weapon after a man was found dead in a city alleyway this morning.
The man, believed to be in his early 30s, was discovered by a member of the public on Collie Street at about 7am.
He was dead by the time police arrived at the scene.
It is believed the man has injuries consistent with a serious assault, but police have ruled out earlier reports which indicated he had been in a fight. The time and cause of his death are still unconfirmed but police are treating it as suspicious.
Police are reviewing CCTV footage from cameras in the area and forensic officers are combing the area.
A number of witnesses have been interviewed and door knocks are being conducted in the area.
Members of the dog squad have been spotted in the area but police could not confirm if they were being used to hunt for a possible killer.
Detectives are calling for any anyone who saw something which may be of interest in the area between 6am and 7am today to come forward and contact 131444 or Crime Stoppers on 1800 333 000.