A man was still fighting for his life today after suffering a head injury in Brighton.
Police do not know whether he was attacked or fell and they are having to treat the case as a possible crime.
The 31-year-old, who was found unconscious on the ground in Selsfield Drive, Hollingdean, on Monday night, has been named as Thorsten Mann, who is originally from Germany.
He was taken to the Royal Sussex County Hospital and was later transferred to a neurological hospital in London, suffering from haemorrhaging in the brain.
Mr Mann has lived for a number of years in Northamptonshire but was a frequent visitor to Brighton where he has friends.
Det Insp Bill Warner, of Brighton CID, said: "The circumstances surrounding his injury are still not known and we urgently need to speak to anyone with information."
Witnesses, who may include three men working on a white van near the scene, at around 11.30pm on Monday, should call police on 0845 6070 999.
The victim is about 5ft 8in, slim and wore a black waistcoat and carried a black rucksack.
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