Which options do i have if I want to help a relative of mine that have apparently a bipolar disorder,?

I don't have a legal power over this person although she is close relative.The situation is getting worst,I'm too far away.And the person who have the legal capabilites to intern her in Mental institution is doing noting but Winning.This person is getting violent every year pass by.she listen to voices and I think she has got a firearm an is constantly treating the people that lives around her.This thing is getting very delicate.