A murder investigation has begun following the death of a man in hospital four days after he was found injured in Norwich.
Norfolk Police were called to Rose Lane car park in St John's Street on 10 February to find a 54-year-old local man with serious injuries.
The man was taken to the Norfolk and Norwich University Hospital where he died in the early hours of Monday.
Two men and two women were released on bail in connection with the incident.
The men, aged 19 and 21 and from the London area, were arrested on suspicion of inflicting grievous bodily harm with intent.
Two women, aged 33 and 49, both from Norwich, were arrested on suspicion of the same offence.
Police have appealed for witnesses to the attack, which happened at about 0130 GMT last Thursday.