A man, aged in his 50s, has died after a car left the A303 yesterday.
It happened near to Amesbury and the westbound carriageway was closed from late afternoon until just before 9pm.
A white Vauxhall Corsa was found at the bottom of a steep bank.
The man was declared dead at the scene and his next of kin have been informed.
PC Pete Williamson, from Wiltshire Police's Collision Investigation Unit, said: "At this stage we do not know what caused the car to leave the road, and we are not clear exactly when the collision happened, although we do believe it happened at some point today.
"We want to hear from anyone who may have any information which could help us understand what happened.
"Perhaps you saw something which at the time didn't cause any concern, but now seems suspicious or could assist our investigation.
"Anyone with information should call Wiltshire Police on 101, quoting log 193 of today (4/6/19)."