A silver Renault Megane was travelling along Great Horton Road out of Bradford when it collided with 39 year-old Andrew Simpson, who was crossing Great Horton Road near to the junction with Old Road at 1.20am on SOctober 1.
Mr Simpson, of Hollybank Gardens, died at Bradford Royal Infirmary.
A 23-year-old Halifax man was arrested on suspicion of dangerous driving and has been bailed pending further enquiries.
They have released a CCTV image of a man who officers believed may have witnessed the collision or the movements of the Renault Megane prior to the collision.
He was walking along Great Horton Road out of the city moments before the collision. He is believed to have been wearing light-coloured clothing and three-quarter-length trousers. Police have said the man is not suspected of being involved in the collision in any way.
If you are the man pictured, or you can identify him, contact Detective Sergeant Carole Clayton of the Major Collision Enquiry Team on 101, or 01924 293047.