A 24-year-old man from Bassingbourn was killed in a collision near Royston.
The crash took place at around 10.30am on Friday, August 4.
A grey BMW 330i M-Sport heading north was involved in a collision with a black BMW 3 Series coming the opposite way, between Royston and Melbourn.
The driver of the BMW 3 Series was pronounced dead at the scene, and the driver of the 330i was taken to Addenbrooke's Hospital in Cambridge with serious injuries.
Sergeant Dan Newton said: "A young man has tragically lost his life in this collision and my thoughts are with his family and friends at this very difficult time.
"I am appealing to anyone who may have seen the collision, or either car prior to it, to get in touch."
Anyone with information or dashcam footage should report it through the force website using reference CC-04082023-0613.
Anyone without internet access should call 101.
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