The four people from Crawley who were arrested on suspicion of murder have been released on bail pending further enquiries.
A 24 and a 22-year-old woman and two 20-year-old men, have been bailed until 9 August.
It comes after the murder of Sam Caulfield from Mayfield, who was found with a serious injury in Crawley. He later died in hospital.
Witnesses can email 101@sussex.pnn.police.uk or call 101 quoting Operation Venture.
Alternatively, you can call the independent charity Crimestoppers anonymously on 0800 555 111 (http://www.crimestoppers-uk.org/).