Where does the family of the 'mentally ill' individual become liable for not protecting the public? 

It's okay to hi-jack a street car, brandish a weapon and expose yourself to the public and then act aggressively towards law enforcement. We know he was an innocent kid with issues but how about keeping him in and surrounding him with family instead of letting him be out and armed? 

If Sammy would have killed anyone would the family be liable for the damages?