What to do with someone who just keeps on killing?

Isn't it kind of funny how despite all the claims of exercising 'restraint' every time Israel deals with unarmed demonstrators the result is a bloodbath? It's like they just can't help but be psychotic mass murderers. Even if they're telling the truth that they don't mean to carry out bloody massacres it just keeps happening that's still a good enough reason why this horrific state must be extinguished. As a national security issue if nothing else. What do you do with someone who just keeps on killing and maiming regardless of their excuses? If someone with a gun kept going round the streets shooting people yet insisting he didn't mean to do it everyone just keeps provoking him would that be an excuse? Even if he genuinely felt that way would he be allowed to continue or would he be forcibly disarmed and put in a secure mental hospital? How many more lives must Israel take before it becomes too much? How many more massacres?