Melbourne Embona detectives are appealing for witnesses after a man attempted to rob a taxi driver in Collingwood last month.
Investigators believe the man was picked up from a Reservoir address around 11pm on Friday 13 September.
The man asked the taxi driver to take him to Collingwood.
When the taxi approached Hoddle Street, the man told the driver he had a gun before making demands to pull over and leave the keys in the ignition.
The taxi driver took the keys and fled to a nearby service station where he called police.
The offender checked to see if the keys were in the ignition before fleeing the scene empty handed.
He was last seen running south along Hoddle Street.
The taxi driver was not injured during the incident.
The offender is described as being Caucasian in appearance, medium build with short dark hair.
He was wearing a navy blue bomber jacket with dark pants.
Detectives have released an image of a man they wish to speak to in relation to the incident.