Moises Meraz-Espinoza allegedly walked into the Huntington Park police station, which is staffed by sheriff's deputies under contract to the city, and told authorities he had killed his mother.
"He came into our station and said to us that he had killed his mother," said sheriff's spokesman Steve Whitmore.
Meraz-Espinoza then led officials to the Maywood apartment he shared with his mother in the 5600 block of Maywood Avenue.
Police did not confirm if the body belonged to Meraz-Espinoza' mother, identified by neighbors as Amelia.
Meraz-Espinoza was booked for suspicion of murder and held without bail.
There were no details released regarding the circumstances surrounding the woman's death.
There have been some reports that the man may have been suffering from depression after his girlfriend was hit by a car and killed four months ago.
Neighbors in the area said they were stunned at the incident and said the mother was a nice woman. She hadn't been seen or heard from since Monday morning.
Inside the apartment bathroom, there appeared to be blood in the shower and on the floor.
The building's owner, Apifino Hernandez, said he spoke to Meraz-Espinoza on Friday. The teen reportedly told the owner that he didn't want him coming to his apartment.
"I was putting in a sink in the kitchen for everybody and he told me not to do his until next week," Hernandez said.
"It's kind of terrifying," said neighbor Franchesca Lopez. "I'm really scared of being around here now because a lot of bad things have been happening."
Neighbors said Meraz-Espinoza was relatively quiet and mostly kept to himself.
The Associated Press and City News Service contributed to this report.