Family is damned if they do, damned if they don't.
There is nothing they can do, for starters. If they do try to warn people, they'll get condemned for not supporting/helping their family, "blood is thicker than...." and all the other societal BS that is patently wrong.
Or if something like this happens, they get condemned for "not stopping it", as if they have a telepathic read on the mind of an asshole simply because they are related, and all the other societal BS that is patently wrong that goes with it.
In practice, people are just estranged until the news comes knocking and says "your dear brother...."
The reality is, our system is made for people like this. And by made for, I don't mean in a positive way. You're not going to fix the symptoms until you address deeper issues, and in this country, it's pretty much impossible.
Feedback
It is terrible to contemplate how few politicians are hanged. - The Cleveland Press, March 1, 1921, GK Chesterton
Everybody is crazy.
It's merely the state of adjustment they are in on any given day that is of question.
The most important thing to be learned from those who demand "Equality For All" is that all are not equal...
Gun Control - seeking a Hardware solution for a Software problem...
One out of four people are mentally ill.
Think about your three closest friends.
If they seem perfectly normal then guess what?
You?re the one.
You can't blame the family. Clearly, law enforcement knew about this whacko and either could not or would not do anything constructive. I would hate to be held accountable for the actions of my eldest sister (a full-on sociopath).
Light a fire for a man, and he'll be warm for a day, light a man on fire, and he'll be warm for the rest of his life...
Discussion is an exchange of intelligence. Argument is an exchange of
ignorance. Ever found a liberal that you can have a discussion with?