Detectives are appealing for witnesses after a shop attendant was threatened with a syringe in the CBD yesterday.
The incident took place at a Swanston Street convenience store at 11am when a man entered the store and told the attendant to hand over any cash he had.
The man, dressed in a high-visibility work jacket, was armed with a syringe.
The quick-thinking attendant stepped back from the counter and activated a security door, following which, the man walked from the store empty-handed.
Investigators have released images of a man they believe can assist with their enquiries.
Detectives urge anyone with information to contact Crime Stoppers on 1800 333 000.