Police have released footage of a man, armed with a long object, suspected of killing another man in the car park of a Melbourne shopping centre last week.
Police believe he was the victim of a targeted attack.
They said a member of the public called triple-0 after finding the man near a lift.
He died of head injuries at the scene, despite attempts to save him by members of a fitness group that had been training nearby.
Investigators believe Mr Dick was attacked as he exited the lift about 6:00am on Friday.
They have released CCTV footage of a man they want to speak to.
The footage shows the man entering and exiting the lift on the day before the killing.
Police said the man is believed to have returned at the same time on the day Mr Dick was killed.
“Investigators believe the footage indicates that the suspect is likely to have targeted David,” Victoria Police said in a statement.
“At this stage there is no known motive for the vicious attack, with David struck without warning as he exited the lift.
“The man then fled down a fire exit before heading south from the car park in the direction of Doncaster Road.”
The suspect is likely to have injured his hand during the attack and may have sought medical attention, police said.
Family pays tribute to ‘the most magical person’
The family of Mr Dick said they did not understand why he was murdered so “viciously”.
His mother Carol Cloke said her son was getting his life together and was in a happy place before his death.
“I’m not quite sure why this has happened but my son has been murdered viciously,” Ms Cloke said.