The woman was found at about 9:15 a.m. outside a home at 5716 Fresno Avenue, Peixoto said.
A homicide investigation had started before the woman's body was examined at the Contra Costa County coroner's office, where it was discovered she apparently died of carbon monoxide poisoning, Peixoto said.
Although the vehicle was relatively new, the coroner said that if the heater is turned on while the car is running and there is no wind, the vehicle's vents can pull the exhaust fumes inside the vehicle, according to Peixoto.
