> The behavior of an armed citizen will be CLEARLY different from a maniacal sociopath walking around a school, church, mall, office, or wherever spraying bullets.
You hope. But how do you know?
A hypothetical mass-killing sociopath who manages to hide behind cover, convince others that he is not the killer, and calls police "acting" like an upstanding citizen, and all while still managing to shoot innocents...is going to be such a rarity it would be statistically negligible. This ain't the movies...someone bent on catastrophic human destruction isn't going to be a cool operator...he is going to go down in flames with lots o' drama. It doesn't pay to overthink the scenario too much. :-)