Garden Grove Police say they found the victim, identified as Vivian Wolff, in a bedroom Tuesday at the apartment she rented on Flower Street.
Detectives say her son, 28-year-old Jonathan Michael Warner, was last seen Friday.
Police say the woman lived with her son and are considering him a person of interest.
Investigators say they want to question Warner to make sure he and other relatives are safe.
The case is being investigated as a homicide.