At the time of the incident, Lt Joe Mendoza says police were talking with Marquez, and the 49-year-old pulled out what appeared to be a real gun. She was then shot at least once in the torso by an officer.
The 49-year-old was taken to hospital and was later pronounced dead.
The bodycam footage shows the officers entering Marquez's home, where she appears to be in distress and screams when officers ask if she is ok.
Police said at the time of the incident paramedics and a mental health clinician spoke with her and said they would take her to a hospital.
"At the time [of the shooting] there was an LA County mental health clinician here with the officers," Lt Mendoza said in 2018.
"They began to communicate with her, she became very uncooperative and during that contact she armed herself with a handgun, she pointed it at the officers and an officer-involved shooting occurred."
The video zooms in on the handgun Marquez pulls out.
The handgun was later determined to be a replica, ABC7 reports. Her family filed a wrongful death lawsuit against the city of South Pasadena.
Prior to her death, Marquez opened up on social media about her struggles with her mental and physical health. She said she had terminal cealiac disease.
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