The victim's 9-year-old daughter called 911 with a frantic plea for help after seeing the brutal attack at about 2 a.m. Saturday in Lancaster.
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 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.
Canales might have a gun and is considered armed and dangerous. If you have any information on where he might be, you are urged to call the Los Angeles County Sheriff's Department at (323) 890-5500.