I believe in having dogs, large, inside dogs, as a precaution. They aren't a guarantee, but they have stepped up often enough in people's experiences to make their expense well worthwhile. When my son lived in our house with us, I could sleep with a loud fan on to block his nighttime noise and the dogs in the bedroom to keep us safe.
A friend from childhood was saved by her large dog. Her daughter with scz had threatened to kill her and a sibling many times. When she was successfully choking my friend, her dog intervened and saved her life.
As I have mentioned before, I tried to get a woman from my FtoF class to get a dog for protection. Her son had threatened to kill her and her husband many times. He killed both of his parents with a sledgehammer.
After that I got a second dog, and we still haven't been threatened by our son - I'm not taking any chances.
Remember if it happens to you, its the scz that's threatening to kill you, not your family member.