Police are investigating whether a woman may have already been dead when a Mercedes collided with her on the M66.
Detectives are analysing CCTV footage as they try to establish how the woman ended up on the motorway in the early hours of yesterday morning.
Part of the M66 was closed for about ten hours yesterday after a car struck a woman's body on the motorway.
Officers were called just before 2am on Thursday to reports that a car had collided with a body in the northbound lanes.
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Emergency services attended the scene and found the body of a woman.
A post-mortem will now take place.
Officers are now appealing to any drivers who were on the road to come forward in case they have any information that might help their investigation.
The woman's family and the driver of the Mercedes are being supported by specialist officers.
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Police Sergeant Joe Barron of Greater Manchester Police's Serious Collision Investigation Unit, said: "This incident caused a lot of disruption throughout the morning and into the day and I know the impact this had on motorists so I'd like to thank them for their patience as we've carried out our enquiries.
"I appreciate from what we know at the moment, this seems an unusual set of circumstances but our team will continue carrying out the enquiries we need to do until we find out exactly what happened.
"As it was early in the morning, there weren't many people in the area at the time but if anyone witnessed what happened or has any CCTV, please contact us as a matter of urgency."
