Thames Valley Police is appealing for information and dash-cam footage of a crash on the M40 which killed one woman and left another in a serious condition.
A grey Ford Fusion left the carriageway into woodland at the side of the motorway between junctions four and five shortly before 10pm on Saturday (December 8).
Ambulance crews attended and the driver and passenger were both transferred to the John Radcliffe hospital.
The passenger of the car, a woman in her 20s, died at the hospital. The woman’s next of kin have been informed and are being supported by officers.
The driver of the vehicle, a woman in her 40s, remains in hospital in a serious condition.
PC Simon Nelson said: “This was a collision in which a woman has sadly lost her life. Our thoughts are with her family at this very difficult time.
“We are continuing to investigate the circumstances surrounding this collision and would like to appeal to any witnesses to please come forward.
“We would ask any motorists who have dash-cam footage of the incident to please contact us.”
Anyone with information should call 101 quoting reference 1470 of December 8.