Detectives from Keilor Downs Embona are appealing for public assistance following an armed robbery at a service station in Deer Park.
Police have been told a man entered the business on the corner of Ballarat Road and Robinsons Road around 12.30am on Friday 15 February wearing a pair of underpants on his head.
The man approached the counter, produced a knife and made a demand for cash.
The staff member handed over a quantity of money before the offender threatened a customer and stole his wallet.
Investigators have been told that the man then left the store and was last seen heading north on Robinsons Road.
Fortunately no one was injured during the incident and the man is perceived to be of African appearance.
At the time of the offence he was wearing a light blue jumper, black pants with stripes, camel coloured shoes with black laces and a pair of black underpants.
Police have released an image of a man that they believe may be able to assist with their investigation.