Update 3.30pm: A man who was found dead in water near Mandurah yesterday has been identified as 46-year-old Ilario Maiolo.
The body was discovered about 11.30am by a man walking his dog along the beach near the intersection of Boardwalk Boulevard and Montego Way.
The man called police when he saw what he believed was a body floating close to shore.
Major crime Det Supt Anthony Lee said Mr Maiolo, who was known as Larry, regularly walked on the Halls Head dog beach.
"We've established he was most likely walking on the beach about 8am on Monday morning," he said.
"We have family members who told us he has gone for a walk down the beach, something has happened there on the beach, potentially, or close to the beach and it's a matter now for us to piece that together and we need the community's assistance in doing that."
It is believed Mr Maiolo never made it home from his walk.
He said it was still unclear where Mr Maiolo died. Police would not reveal how they believed Mr Maiolo was killed or whether a weapon was used.
Police raided a property earlier today and took a man into custody for questioning over the discovery.
Det-Supt Lee said police still needed public help to establish what happened and wanted to speak to anyone who had been at the beach yesterday morning before 9.30am.
"If you're a resident of that area and you observed activity that morning and you think it may be related, please take the time to call police," he said.
Homicide detectives want to speak to a man who was near the Halls Head dog beach or Mandurah Country Club Golf Course in the hours before the body was found.
The man police want to speak to is described as tall and fair skinned and is understood to have been riding a bicycle and with a large dark dog.
Police divers are searching the ocean near where the body was found.
Police yesterday sealed off parts of the beach and closed a section of footpath between Montego Way and Calypso Road.
They later cordoned off a home in Calypso Road, saying it was a site of interest. SES volunteers today are searching bushland near a water treatment plant on the road.
The man’s name has not yet been released and his death is being treated as a suspected homicide.
Anyone with information is asked to call Crime Stoppers on 1800 333 000 and callers may remain anonymous.