An 81-year-old man died after coming off his scooter during a collision in Lawkholme Lane on February 15.
Now officers are searching for two cars that were travelling alone the road at the same time - about 1pm.
Sergeant Ann Drury, the senior investigating officer, said: "We urgently need to speak to the occupants of these vehicles as we believe they may have information which could assist our enquiries.
“If anyone recognises either of these vehicles or who may have been driving them in Lawkholme Lane at just after 1pm on 15 February, we would urge them to contact us, so we can make further enquiries and progress our investigation.”
The images released by police show a silver car, thought to be a Honda Accord registered between 2002 and 2005, and a purple car believed to be a Ford Fiesta.
Anyone who can assist the investigation is asked to contact the Major Collision and Enquiry Team on 101, quoting reference 13180076831.