Thames Valley Police are asking Milton Keynes residents if they can help with an appeal issued by Herts Police.
Officers are appealing for witnesses, information and dashcam footage following a fatal road traffic collision on the M1.
The incident occurred near to junction 6A just before 5am yesterday (Monday 31 July).
It is reported that two vehicles, a Kia and a BMW collided on the southbound carriageway.
Two people, who were travelling in one of the vehicles, left the scene prior to police arrival.
Shortly after, police were called by the ambulance service to report a separate road traffic collision on the M1 northbound involving a van and a pedestrian.
Sadly, a 58-year-old man who was the pedestrian was pronounced dead at the scene. The family have been informed and are being supported by officers.
Sergeant Ian Manley, from the Road Policing Unit, said: “Our thoughts are with the man’s family at this very difficult time.
“Our enquiries into the collisions are continuing, but at this time we are treating them as linked. We believe the man who passed away was travelling in one of the vehicles involved in the first collision. We are still working to trace the other person who left the scene prior to our arrival.
“I am particularly interested in speaking to a coach driver who was driving north on the M1 at the time of the incident and may have crucial information to help with our investigation.
“Did you see what happened, or have any information that may help our enquiries?
Additionally, if you were driving in the area and have a dash cam fitted, please check it as you may have recorded come crucial footage that could assist our investigation.”
Anyone with information is asked to contact Sergeant Manley via ian.manley@cambs.police.uk.
You can report information by filling out an online reporting form at here or speaking to an operator in their Force Communications Room via online web chat here.
Yuo can also call the non-emergency telephone number 101 (in an emergency, always dial 999) or contact Crimestoppers anonymously on 0800 555 111.
Please quote ISR 64 of Monday 31 July.
