An armed robber stole several iPhones from a shop in Brighton yesterday (Tuesday 16 August).
The robbery is being linked with two others in Hove and Worthing last month.
Yesterday the suspect went into Replay Exchange in Western Road, Brighton, armed with a hammer at about 9.25am as the manager was opening up.
He told the manager to get down on the floor, jumped over the counter and grabbed several iPhones.
He made off towards Churchill Square on a BMX-style bicycle.
Last month – on Saturday 13 July at about 12.30pm – a man went into Carphone Warehouse in George Street, Hove, and threatened staff.
He used wirecutters to steal two mobile phones before escaping on his bike.
The same thief is believed to have robbed Carphone Warehouse in Montague Street, Worthing, at knifepoint at about 9am on Thursday 7 July.
He stole two mobile phones before riding off up Montague Street,
Detective Constable Scott Moore, from Brighton and Hove CID, said: “Due to the times of the robberies and the modus operandi, we believe all three may have been committed by the same man.
“Fortunately, no staff were injured but it is nonetheless, a frightening experience and all three shops have lost thousands of pounds worth of phones.
“Officers are conducting house to house inquiries and speaking to local businesses.
“We would like to advise mobile phone premises to please be alert when opening up in the morning.
“Dial 999 immediately if you see anyone acting suspiciously and make sure that your CCTV is working.”
The suspect is described as a black man, about 5ft 5in to 5ft 7in tall, in his late teens to mid twenties, of thin build with very dark skin and short black hair.
During the Brighton robbery the suspect had two shaved lines on the left-hand side of his head.
In the Worthing robbery he was sporting a distinctive “chin-strap” beard and thin moustache.
In the Hove robbery the suspect was wearing a grey hoodie, jeans, black trainers and a dark blue backpack.
During the Worthing robbery he was wearing a light grey woolly zip up jumper, possibly with darker grey fur lining the hood, baggy light blue jeans and trainers.
He was also wearing a Russian-style winter hat which had grey fur at the forehead and ear flaps and tan-coloured fabric covering the head.
Sussex Police said that it would like to hear from anyone who has information about the suspect or who has been offered mobile phones for sale.
Witnesses should call Sussex Police on 0845 6070999 or the independent charity Crimestoppers anonymously on 0800 555111.