A man sustained serious injuries after being hit by a car in Great Denham in the early hours of on Saturday 28 August.
The incident happened on the north-west part of the Branston Way.
Emergency services were called at around 3.30am.
The vehicle’s driver is co-operating with police enquiries.
Sergeant Russell Jones from the Bedfordshire, Cambridgeshire and Hertfordshire Roads Policing Unit said: “We are keen to hear from anyone who may have been in the area at the time and witnessed the incident.
“If you think you may have seen the man prior to the incident or have any dash cam footage of the area then please get in touch.”
Anyone with information should call 101 or report it online here.
