It's emerged a car was not discovered for over 13 hours after it overturned near St Brides Major.
Police officers investigating the incident believe it happened at around 6pm on Sunday 9th November - but the car was not discovered until around 7.30am the following morning.
The sole occpant of the vehicle died at the scene.
A South Wales Police spokesperson said: "Anyone who may have been in the area at the time who may have witnessed the manner in which the vehicle was being driven is urged to come forward. Motorists are urged to check for relevant dashcam footage of the incident."
Anyone with information should contact South Wales Police on 101 or use the live web chat, quoting reference no. 2500358199. Alternatively, contact Crimestoppers anonymously on 0800 555 111.

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