Lambton OPP say a man involved in a single-vehicle crash on Hwy. 40 in Sarnia, died as a result of a pre-existing medical condition.
Just after 3pm on Friday, Ontario Provincial Police, Lambton EMS and Sarnia firefighters responded to Hwy. 40, south of Wellington St., where they found a vehicle in a field on the west side of the highway.
Police say a 79-year-old Plympton-Wyoming area man was transported to hospital where he was later pronounced dead.
Subsequent investigation and a postmortem conducted on Sunday determined the man did not die as a result of the crash.
The man's name is being withheld.
Hwy. 40 between Wellington St. and Confederation Line was closed for several hours for the investigation.