Police have closed a stretch of the M1 after a body was discovered on the motorway.
Northamptonshire Police said the road was expected to remain partially closed for most of Tuesday after the body was found, some time before 3am.
Highways England said the "serious incident" closed the northbound carriageway between junction 16 near Northampton and junction 18 near Rugby.
Northamptonshire Police said: "Motorists are advised to seek alternative routes and diversions will be in place."
Anyone with information should contact police on 101 or Crimestoppers anonymously on 0800 555 111.