A 16-year-old girl who was stabbed in her house used her last breath to name her ex-boyfriend as the killer.
The girl's screams woke up her mother just after 3am (local time) in the quiet neighbourhood in Pico River, southeast of downtown Los Angeles.
Elena Lillian Moore had been stabbed at least once in the chest, and she collapsed and died in front of her mother a short time after yelling the name "Rory".
Investigators were searching for Moore's 17-year-old former boyfriend, Rory Murga.
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Evidence found at the crime scene also tied Murga to the home, Lt. Eddie Hernandez said.
"She was yelling and screaming his name. It's horrible,' Hernandez said.
"Can you imagine waking up to the screams of your daughter at 3.15am in the morning and this happens? It's unthinkable."
A kitchen knife believed to be the weapon used in the attack was recovered inside the home, Hernandez said.
It was unclear whether she let her killer into the home or whether the attacker broke in, he said, adding that damage found to the back door could have happened in the past.