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.
Where to get help: • Lifeline: 0800 543 354 (available 24/7) • Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7) • Youth services: (06) 3555 906 • Youthline: 0800 376 633 • Kidsline: 0800 543 754 (available 24/7) • Whatsup: 0800 942 8787 (1pm to 11pm) • Depression helpline: 0800 111 757 (available 24/7) • Rainbow Youth: (09) 376 4155 • CASPER Suicide Prevention If it is an emergency and you feel like you or someone else is at risk, call 111.
