The fatal collision occurred just before midnight on Sunday 18 May 2014, on the A6055 Ferrensby to Knaresborough road, close to the entrance road to Knaresborough Golf Club.
Police are appealing for a vital witness to come forward.
The man officers need to trace had been travelling from the Knaresborough direction and arrived at the scene shortly after it occurred. It is believed he used a torch and high visibility clothing for himself and another motorist at the scene. However, he left before the arrival of emergency services without leaving his details.
Traffic Sergeant Pete Wood, of the Force’s Roads Policing Group, said: If you are the man who stopped to offer assistance at the scene, I urge you to get in touch with the police straight away as you may have vital information which could assist this investigation.
I am also keen top speak to anyone else who can help with this enquiry and ask them to get in touch.
Anyone who can assist officers with this investigation should contact North Yorkshire Police on 101, select option 2 and ask for Mark Paterson. Alternatively, information can be emailed to email@example.com