A quad bike rider killed in a crash near Bicester has been named as Christopher Abbott, as police search for a car they believe was near the scene.
Officers have asked the occupants of a dark-coloured estate car to come forward after the fatal crash on the A4095 between Chesterton and Kirtlington between 7.30pm and 7.45pm on Monday, April 3.
Mr Abbott was taken to hospital and died there on Tuesday, April 11.
The force has now issued a fresh appeal for information, and believe those in the car may have seen the crash.
Investigating officer PC Phil Hanham of Bicester roads policing said: "We are continuing to appeal for witnesses to this collision, in which a young man sadly lost his life.
“In particular, we would like to speak to the occupants of a dark-coloured estate car which was believed to have been in the area at the time of the collision and its occupants may have witnessed what happened.
“If anyone witnessed the incident or has any information, please call Bicester roads policing on 101, quoting incident number 1440 of 3 April 2017.”