POLICE are treating the discovery of a human head washed up on a Rottnest Island beach as a homicide investigation.
A young girl beachcombing with her family at Porpoise Bay, on the southeast of the island, discovered an item wrapped in a plastic bag just after 4pm on Sunday, PerthNow reports.
She opened the bag and saw what looked like a human ear, and the family immediately contacted police.
Major Crime Squad's Detective Senior Sergeant Cameron Western said the bag and its contents were taken to be examined at the state mortuary.
A post mortem examination is currently underway, but police have confirmed the head is of an adult male who they believe was aged between 30 and 50.
"The plastic contained the remains of a male Caucasian head ," Det-Snr-Sgt Western said.
"The male had no piercings in his ears. He was missing his front upper teeth and that' s not recent...he was missing his front upper teeth before he met whatever fate he's met."
Last night, detectives from the Major Crime Squad and forensic officers were ferried to the island, a popular holiday spot 18km off the coast of Perth, and spent today examining the scene.
Porpoise Bay has been declared a protected forensic area and is closed to the public and media.
"Over the coming days, Porpoise Bay and the southern side of Rottnest Island will be searched and police divers will also be conducting searches in the area surrounding where the remains were located," Det-Snr-Sgt Western said.
"We have identified the boats that were in the bay and we'll be speaking with occupants of all of those boats.
He said police were also consulting with experts on sea currents and were scouring missing persons registers in WA and across Australia.
Investigations are underway to identify the man using forensic methods.
Read more at PerthNow.