The body found on the carriageway of the M9 motorway has been identified as a teenage boy.
Police from the Forth Valley area have named Michael Easton, 13, from the nearby town of Polmont in Falkirk as the person found on the westbound carriageway of the M9 between Junction 5 and 6 near Cadger's Brae, Grangemouth at 5.40am.
He was last seen at 9.50pm on Friday night in Grangemouth and was expected home around that time.
Officers are investigating the circumstances of his death and would like to hear from anyone who may be able to help with their inquiries.
Detective Inspector Graeme Hendry said: "We are still in the early stages of trying to establish what happened to Michael and we believe motorists who were on the M9 around 9. 50pm on Friday night can be of assistance to us.
"Anyone who was travelling on the road at this time and remembers seeing anything that can help our investigation is asked to contact police on 101 immediately .
"Similarly, any driver or vehicle passenger who believes that they may have witnessed anything, or been involved in a collision in or around this time is also asked to come forward."
The M9 was reopened in both directions at 6.30pm.