Click in the Eyewitness News Story Window above to watch Jovana Lara's report, including the 9-year-old's 911 call.
The young girl placed the call from the couple's apartment after she and her three young brothers allegedly watched their father, 28-year-old Jesus Canales, murder his long-time girlfriend, 26-year-old Lucy Preciado, with a 3-foot-long sword.
Girl: Hello, my dad just stabbed my mom.
911: He just what your mom?
Girl: He just stabbed my mom.
911: What did he stab her with?
Girl: A sword.
911: A sword?
Detectives described the killing as the worst they had ever seen.
"To think about the trauma that was introduced into the children's lives, the tape, as you heard, is just gut-wrenching, and it affects everybody who becomes familiar with the case," said Lt Dave Dolson from the Los Angeles County Sheriff's Department.
Detectives believe Canales is driving a bronze 2002 GMC Safari van, with California license plates with tag number 6CBY663. Canales may be carrying a pistol and is considered armed and dangerous.
Anyone with information is urged to call the Los Angeles County Sheriff's Department at (323) 890-5500.