Norfolk Constabulary is being investigated following the death of a man after a police chase, the police watchdog has announced.
Officers were pursuing a Citroen C3 on the A47 near Little Fransham, at about 17:00 BST on 23 May when it left the carriageway and overturned.
The man, 43, of March, Cambridgeshire, died in hospital on 29 May.
The Independent Office for Police Conduct (IOPC) said it was in the "early stages" of its investigation.
IOPC Regional Director Sal Naseem said: "Our thoughts are with this man's family and friends, and all those affected by his death.
"There is a mandatory requirement for forces to refer to us incidents like this which result in death or serious injury and our investigation will thoroughly examine the circumstances of the police involvement, including whether appropriate policies and procedures were followed."
The IOPC said it had gathered initial accounts from officers involved and started a review of police body-worn footage, dashcam footage and CCTV.
Norfolk Constabulary has been asked to comment.