Homicide Squad Detectives and Forensics are probing a Cooper Street property after a man was found dead on Friday afternoon.
A 23-year-old man was located deceased in the rear shed of the Cooper Street property.
Officers have cordoned off a section of the central Mandurah street between Park Road and Dower Street.
Detectives and police worked through the night and were seen knocking on doors in surrounding streets asking for information.
Neighbours told Skeer Media that the house was allegedly vacant.
A WA Police spokesman said the death hadn’t been ruled out as non suspicious.
Investigators are appealing for anyone with information to contact Crime Stoppers by calling 1800 333 000 or online at crimestopperswa.com.au