A 22 year-old motorist died after a crash on the B645 between Hail Weston and Staughton Highway, near St Neots, at about 6.40pm on Tuesday, 27 August.
A white Vauxhall Astra had been in collision with a white Mercedes lorry and the driver of the Vauxhall, a 22-year-old man from the Rushden area, in Northamptonshire, was pronounced dead at the scene.
The passenger in the Astra, a 22-year-old woman from St Neots, was taken to hospital with serious injuries.
A 63-year-old man, from the Sleaford area, in Lincolnshire, who was driving the lorry, was uninjured and remained at the scene.
Sergeant Ben Chance said: “I would like to hear from anyone who saw or has dashcam footage of the crash, or the vehicles involved just before.”
Anyone with information or dashcam footage should report it through the force website using reference CC-27082024-0466.
Anyone without internet access should call 101.