It's America, there's a tragedy or outrage, so obviously you look for the conspiracy. If it's South it must be them damn Yankee Feds. If it's North it must be them damn gun toting rednecks of the NRA. America has a conspiracy theory for everything from flat Earth to lunar landings. Long may it continue, might not stand up to critical examination, but it always intrigues you. As a Brit the main thing that got me is why the hell are ATF in the same building as a childcare centre, what next, FBI offices above the retirees home. We pour scorn on others we say are using human shields, no military, intelligence, or enforcement agency should be anywhere near these places.As for the basic premise it's the old story, possibility / probability / definitive. Depending on viewpoint you'll choose the one you prefer, I'll choose the wonderful Scottish cop out verdict - NOT PROVEN. :-)