Enquiries suggest the Asian woman, who may have been in a black car, stopped to help following the single vehicle collision in Bowling Back Lane on Sunday, when a grey Audi Q7 left the road and struck a wall at about 1.30pm.
The vehicle had been travelling along Birksland Street minutes before.
A 22-year-old man was sadly pronounced dead at the scene and four other males in the vehicle also received treatment for their injuries at hospital.
A 22-year-old man from Bristol was arrested on suspicion of causing death by dangerous driving and has since been released under investigation.
Sgt Ann Drury, of the Major Collision Enquiry Team, said: “We are keen to speak to this woman as she may have information which could be vital to our investigation. I would urge her to contact us as soon as possible so we can progress our enquiries into this tragic incident.”
A police spokesperson confirmed that they have now spoken to the occupants of a white Volkswagen Golf following an earlier appeal.
Anyone else who can assist the investigation is asked to contact the Major Collision Enquiry Team on 101, quoting log 0791 of 21 January.