Major Crash officers are still searching for a Black Ute involved in the crash.
A 56 year old man has died after he was involved in a traffic crash in Cockburn Central.
Around 1.40pm yesterday the man rode his black and silver 1993 model Harley Davidson motorcycle onto the Kwinana Freeway from Beeliar Drive, when he crashed with a semi-trailer and possibly a black vehicle as they were all merging into the northbound freeway traffic.
The victim received life threatening injuries and was rushed to Fiona Stanley Hospital where he died a short time later.
Major Crash officers would like to speak to the driver of the black vehicle described as a Commodore or Falcon Ute with a dark or black fibreglass canopy.
The vehicle was on Beeliar Drive and turned left into the slip lane and then north with other traffic on the freeway.
Investigators are urging anyone who aided the motorcyclist at the scene, or who saw the crash, to call Crime Stoppers on 1800 333 000 or make a report online at www.crimestopperswa.com.au

Early voting for Secret Harbour by-election begins Monday
Welfare concerns for missing Swedish national last seen in Warnbro
Wanted man last seen in Golden Bay
Passenger critically injured in West Pinjarra crash
Unregistered painter fined for requesting hefty deposit from Singleton homeowner and not doing the job
Police hunt driver following dangerous Baldivis pursuit
Welfare concerns for boy last seen at Port Kennedy skate park
Rubbish truck catches fire in Baldivis
Driver injured in bus crash in Rockingham