A 42-year-old woman was identified Thursday in the death of her mother-in-law.
Un Young Lee, of San Dimas, was booked into jail on suspicion of murder in the death of the woman, who has not been identified, said the Los Angeles County Sheriff's Department in a news release.
The woman is believed to have been killed at a Diamond Bar home that caught fire early Wednesday. Lee was detained in Tustin, where officials found a body inside the suspect's vehicle.
Fire crews searched the home after dousing the flames and did not find anyone inside.
Hours later, police stopped a "suspicious vehicle" being driven in Tustin by a woman who lived at the Diamond Bar home, authorities said.
Investigators suspected the remains of her mother-in-law might be inside the car, officials said.
It was unclear what prompted Tustin police to stop the vehicle or what led them to suspect that a body might be in the car.
