Police are seeking the driver of a car in connection with the discovery of a body on a motorway.
Motorists suffered lengthy delays when the M20 in Kent was closed, initially London-bound, after the body was found - and then also coast-bound following an accident.
Officers were called to the motorway between junctions 10 and nine, near Ashford, Kent, at 6.05pm on Tuesday after a body was found. The person was pronounced dead at the scene.
Then at 8am on Wednesday, four cars and a lorry were involved in a collision on the coast-bound carriageway, forcing it to be closed to all traffic. It has since reopened in this direction.
Police have appealed for the driver of a silver Nissan Qashqai, or anyone who saw the car driving on the M20 between 5.30pm and 6.30pm on Tuesday, to contact them.
A Kent Police spokesman said: "Detectives believe the driver of a car, with registration KY15 WWX, may have important information relating to the incident.
"Additionally, anyone who may know the location of the vehicle is urged to contact the police.
"Officers are also appealing for motorists to check their dash cams and their vehicles for any sign of a collision."
The 42-year-old male driver of the lorry involved in the accident on Wednesday has been arrested on suspicion of dangerous driving and remains in police custody.
A woman was airlifted to a London hospital with injuries and a man was taken to a local hospital following the crash.
Witnesses at the scene said they had been at a standstill for about two-and-a-half-hours.
By 10.30am on Wednesday, drivers were experiencing six miles of queues back to junction 11 on the London-bound carriageway, and the road closure was affecting travel to the Eurotunnel and the Port of Dover.
The Kent and Essex Serious Crime Directorate, which investigates incidents including murder and organised crime, is working with road collision investigators to determine the cause of death in the first incident, which is currently being treated as unexplained.
Detective Chief Inspector Richard Vickery said: "We do not underestimate the impact that closing this stretch of the motorway has on people and I thank them for their patience. It is crucial that we ensure that all evidence is collected. As soon as the motorway is reopened the opportunity to collate potentially crucial information is lost.
"We are working tirelessly at the scene and I am hopeful the M20 will be reopened shortly."
A large green screen has been put up where the body was found, and a line of police officers wearing white protective covers on their feet has been seen slowly walking the stretch of the carriageway towards the screen while examining the surface.