COSTA MESA – A woman drove for months with a dead mummified body in her passenger’s seat before the body was discovered by police, authorities said.

Police are still trying to determine the exact cause and time of death of the unidentified woman, but the body of the woman had withered to roughly 30 pounds by the time it was discovered, authorities said.

Costa Mesa Police officials declined to identified the driver of the midnight-blue 1997 Mercury Marquis, but said she was a 57-year-old former real estate agent who at one time lived in a home in Corona del Mar.

After finding the body inside the four-door vehicle, the woman told investigators she was afraid to report the body to police, and instead decided to continue using the vehicle while the body sat covered in clothes on the passenger’s side.

The deceased woman was known to the driver only as Signe, a transient woman from the Fountain Valley area, said Sgt. Ed Everett.

The car is registered to the driver’s sick father, Everett said.

The driver told police she was afraid to contact police about the body, so she continued to use the car.

According to the advanced state of decomposition, officials believe the woman had been dead anywhere from three to 10 months, Everett said. The lack of air inside the vehicle, and weather conditions at the time of death, are believed to have contributed to partial preservation of the body.

Investigators are waiting for toxicology tests and will be looking to using DNA or dental records to identify the woman, he said.

Investigators said the driver of the car had befriended the woman at Mile Square Regional Park and allowed her to sleep in the car overnight in December. That was the last time she saw Signe alive, Everett said.

It wasn’t until Monday that the body was found by police, after receiving a call of a car partially blocking a driveway at the 2000 block of Tustin Avenue.

The driver, who has also fallen on difficult financial times, was staying at a friend’s home in the area, Everett said.

Officers were able to smell a foul odor coming from the car, and after seeing a leg underneath a pile of clothing on the seat, broke a window to get access inside.

Inside the car, officers also found a box of baking soda that the driver used to try to dissipate the smell.

“This person was somewhat used to the smell,” Everett said.

An autopsy has revealed no obvious signs of foul play, but the cause of death is still unknown, he said. Officers are also looking at whether there were any health code violations due to the fact that the driver was transporting a corpse, he said. The driver has not been cited or arrested.

Officers are still trying to determine the identity of the woman, who is believed to be between 50 and 60 years old.

Contact the writer: shernandez@ocregister.com or 949-454-7361