A man was pronounced dead at the scene by police after they found him trapped between a van and a barrier on the M1.
The van was discovered on the hard shoulder on the northbound carriageway between junction 22, Markfield, and junction 23 for Shepshed at around 10.30pm on April 3.
Detectives are now asking for anyone to come forward who may have seen a white Mercedes Sprinter van on the motorway during the evening.
Detective constable Pete Davies, from Leicestershire Police’s serious collision investigation unit, is now investigating the incident.
He said: "I am asking for anyone who was travelling on the M1, especially on the northbound side, to come forward if you saw a white Mercedes van on the hard shoulder.
"Did you notice anything untoward or did you see the vehicle prior to it stopping? If you have a dashcam in your vehicle, please check it for any footage it may have recorded.
"Call 101, quoting incident 737 of 3 April."
An East Midlands Ambulance Service spokeswoman added: "We received a call at 10.38pm on 3 April from our colleagues in the police force requesting medical assistance at on the M1 Northbound between Junction 22 and Junction 23.
"We sent two paramedics in ambulance cars, a doctor in a car and a crewed ambulance."
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