Lincoln County police are investigating the circumstances of a car crash that left one 63-year-old woman dead and her 23-year-old son injured.

The man was able to pull his mother from her sinking pickup truck after it crashed into Moraine Lake at a Harrison shore. Emergency workers arrived in time to transport the man to a nearby hospital to be treated for minor injuries.

Police are uncertain as to what caused the crash, whether the woman lost control of the vehicle due to mechanical failure or driver error or if foul play was involved. The results of the coroner's autopsy have not been release to the public for police fears that it might comprise their ongoing investigation. The toxicology report from the crash will be released, and is expected to be made public by next week. The Lincoln County Sheriff's Department noted that it was working with the Wisconsin Department of Criminal Investigation in order to double-check their results.