Detectives from Whittlesea Crime Investigation Unit are appealing for public assistance following the attempted theft of a vehicle in Lalor last month, Victoria Police say.
A 70-year-old man parked his van on Dalton Road when a powder blue Ford Falcon with no registration plates pulled in front of him about 9.30am on 21 October.
The offending driver exited the vehicle and approached the victim.
The man has produced a black handgun and demanded the victim exit the vehicle.
The victim lay down in his van for protection before the offender returned to his car and drove away.
He was last seen heading east along Childs Road in Lalor.
Detectives have released a computer generated image of a man who they believe may be able to assist with their enquiries.
The man is described as aged between 16 and 18 years-old with dark black hair shaved on the sides.
He was wearing a dark-coloured t-shirt and black pants.
Anyone with any other information is urged to contact Crime Stoppers.