Whittier police responded to the 12800 block of Stardell Street shortly after noon, where the woman was found behind a home, police said.
Investigators said it was not immediately known how the person died.
Police said officers arrested a man at the scene who is related to the victim. There were unconfirmed reports that the man was the victim's son.
Investigators said there were items overturned inside the home, which indicates there may have been some sort of struggle before the murder.
A female who was present at the time of the crime was being interviewed, as authorities worked to determine a motive.
There were no other outstanding suspects, and there is no threat to the community, police said.
An investigation was ongoing.