A care worker was caught placing a cloth over an elderly mans mouth and assaulting him.
Noleen Hausler had become concerned for her 89-year-old father Clarence, and placed a hidden camera in his room to check that everything was okay.
What she found shocked her. The footage showed Corey Lucas suffocating her elderly father by placing a napkin over his mouth and nose, as well as jabbing food into his mouth.
Lucas has been jailed for the assault after footage was passed to police.
Ms Hauser, who is a nurse, said: Being confronted with the visual images, I went into a state of shock and total concern for Father.
My heart was racing (and) my hands were shaking.
The abuse was filmed in September 2015 at Mitcham Residential Care Facility in Adelaide, operated by Japara Healthcare.
Ms Hauser gave evidence at a hearing into what happened at the aged care royal commission in Perth on Monday, the Daily Mail reports.
I had no idea that someone could possibly do that, she said. I felt for dad in the fact that I didnt protect him sufficiently.
The commission is examining whether Japara prioritised its own corporate interests and reputation over person-centred care.
Ms Hausler, whose father died in January 2017, said while some staff were dedicated and compassionate, Japara had a profit-driven attitude.