DA Gregory Oakes said, the Onondaga County Medical Examiner looked at the remains with the assistance from a forensic anthropologist and they could not determine the cause or manner of her death.
Carol Wood's remains were found in a car in the Oswego River in Fulton in June.
Wood's disappearance after leaving a bar in the city of Oswego in 1996 has been a topic of speculation for many years in Oswego County.
Investigators say she had a loud argument with a man there, stormed out and drove away alone in her red 1993 Toyota Corolla.
The family is still looking for answers after the medical examiner's report.
"I'm not going to stop prodding and looking to find out what happened to her and if anybody has any recollection of 18 years ago, if they happened to be in the area, hopefully they'll come forward," said Wood's sister, Alison Gunberg.
The family will hold a burial service for Wood on Sunday, Aug. 31 at Grace Lutheran Church in Oswego.
Police are still investigating the incident.
Police and the District Attorney are asking people who might have information that can help in their investigation to call (315) 342-8120.
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