Just before 2.30am on April 6, police were called to a service station on King Street after a man wearing a Halloween style mask entered the service station armed with a knife and demanded cash and cigarettes from the console operator.
The man managed to steal a quantity of cigarettes and cash and departed on foot, last seen heading south on London Street.
The service station staff member was uninjured.
Police say the suspect is described as late teens to early 20s, between 160 and 170cm tall with a slim build.
He was wearing a orange/red hooded jumper with markings to the rear, grey track pants and black sneakers.
Police urge anyone with information that can assist the investigation to contact Crime Stoppers on 1800 333 000.
Extracted in full from: Police investigate Port Lincoln service station robbery | Port Lincoln Times | Port Lincoln, SA