Lambton OPP say 14-year-old Karen Ann Caughlin was last seen on the night of Friday, March 15, 44 years ago.
Her body was found at mid-morning the next day 22 km away near the side of what was then the 6th Side Rd. or Freer Rd., now known as Plowing Match Rd., between Churchill Line and LaSalle Line.
Police are marking the sombre anniversary by reminding the public that the girl's 1974 death remains an active investigation.
The OPP believes Karen may not have been deliberately killed, and that her injuries are consistent with being the victim of a tragic collision with a motor vehicle.
A $50,000 reward for information remains in effect.
Anyone with information should call Lambton OPP at 519-882-1011 or Sarnia-Lambton Crime Stoppers at 1-800-222-8477.