Western Australia’s major crime squad believes the head may have been dumped in the water prior to washing ashore and are investigating currents and shipping movements throughout the region.
High frequency radar systems deployed by the Integrated Marine Observing System (IMOS) through the Australian Coastal Ocean Radar Network (ACORN) facility are providing valuable information to marine scientists assisting the investigation.
Leader of the Western Australian node of IMOS, Professor Chari Pattiaratchi, is mapping surface currents and examining results from the radars to determine the possible path of the head in the region to the south of Rottnest Island.
Professor Pattiaratchi said that observing infrastructure in the water and research into the shelf currents allowed scientists to estimate the head’s origins.
“Research conducted over the past 20 years has increased our understanding of currents in south west Australia. The discovery of the Capes Current, which brings cold water from the south along the coast of Rottnest, is particularly relevant to this case,” he said.
“The head must have entered the water south of Rottnest - somewhere between Rottnest and Mandurah but west of Garden Island. The current would have carried it north at about one kilometre per hour.”
Police have identified the deceased man, but are still investigating the murder.