The same man is suspected of robbing two Hove betting shops on the same day, threatening staff with a knife during the second hold-up.
He told staff that he had a gun in a branch of Ladbrokes in Portland Road, Hove, at about 1.50pm on Thursday (5 July), although no weapon was seen.
Sussex Police said that he made off with about £300 and was last seen running away into Tamworth Road.
Detectives believe that the same man also robbed the Ladbrokes in Church Road, Hove, at knifepoint just before 10pm on Thursday, making off with several hundred pounds.
None of the staff were hurt and there were no customers in the shops when they were robbed.
Detective Sergeant Chris Sherwell said: “We believe the same man committed both robberies and this was clearly very traumatic for the staff in the two shops.”
The suspect was described as a slim white man, about 5ft 10in tall, in his late twenties or early thirties, with a few days’ stubble and a bald or shaved head.
Detective Sergeant Chris Sherwell said that he was wearing a blue or dark jacket.
He urged anyone who was in the area at the time of the offences or who had any other information to contact Sussex Police by calling 101.
Witnesses can also call the independent charity Crimestoppers anonymously on 0800 555111.
