Authorities discovered the body of Autumn D. Vinson, 62, in a Pontiac Bonneville submerged in five to six feet of water east of the Red Star boat access area, the Cape Girardeau Police Department reported Friday.
Clifton said the toxicology results will not be available for several days and the investigation is continuing.
In an email to the Southeast Missourian, Darin Hickey, public information officer for the Cape Girardeau Police Department, wrote, "The manner of death, what [led] to the vehicle going into the water, is still under investigation."
Hickey said Friday the body was found in the back seat of the vehicle, but it was impossible to tell how it got there, because the submerged vehicle was full of water.
At this point, authorities do not know when or how the vehicle ended up in the river, Hickey said Friday.
A passer-by called police at 10:11 a.m. Friday to report seeing the antenna and roof of the vehicle in the water, Hickey said.
It took crews several hours Friday to remove the car from the river after a first attempt damaged the car's front fender. A tow truck was finally able to pull the car onto the boat ramp about 3:15 p.m.