The discovery was made around 4:00 p.m. Monday in the area of Kelly Drive and Hunting Park Avenue.
That location is about a half mile from where a car went into the river.
Witnesses say the woman's car sped across Kelly Drive, smashed through a retaining wall, and plunged into the river Thursday afternoon.
The driver managed to get out of the car, screamed for help, but was swept away by the current.
A tow truck pulled the 2008 silver Mercury Grand Marquis that night.
The woman behind the wheel was not the owner of the car. Police have talked to the owner, however, and he allegedly told them he had lent the Mercury to a friend.
Police say until they are certain that it was the friend at the wheel, they will not release the name.
Still unanswered is why the car didn't stop. Police will conduct a mechanical inspection of the car, looking for a stuck accelerator or faulty brakes.