The Uckfield man who died in a car crash near Burgess Hill on Sunday has been named by police as James Smith of Tainters Brook.
Mr Smith, aged 29, was the passenger in a Ford Ka that was in collision with a Volvo S40 on the B2112 between Wivelsfield and Ditchling Common, outside St George's Retreat at 1.07pm.
The 27-year-old driver of the Ka remains in the Royal Sussex County Hospital at Brighton where he is being treated for a collapsed lung and a broken pelvis.
Police say the occupants of a blue Volkswagen Polo may hold key information about Sunday's crash.
Sergeant Alan Spicer from Sussex Police Road Policing Unit said: “Witnesses have told us that a blue Volkswagen Polo was travelling south behind the volvo at the time of the collision and would have seen the events unfold.
“The vehicle wasn't involved in the incident, but the occupants may well have vital information that could help us discover how this young man came to meet his tragic death.”
Witnesses are asked to call sussex Police on 101 quoting Operation Caldbeck.
Here is the Uckfield News initial report of the crash: Uckfield man dies in car crash.