Police are concerned for the welfare of a man with a head injury who approached a member of the public in Worthing on Sunday asking for help.
The man told the member of the public in Wordsworth Road that his car had been stolen and that he had been assaulted, according to police.
But when the member of the public offered to call the police and ambulance service, the man 'refused and ran away', police said.
Police were called to the scene at around 8.45pm after receiving a report from the member of the public, who was concerned for the man.
A spokesman said: "If you are the man in question or noticed a man with head injuries in this area at this time please report online or call 101 quoting 1133 of 31/03."