Hey, Mister...
Throwing a rifle off the roof (off camera sight) and picking it up afterwards to hide it in the woods nearby is not really Houdini level magic, isn't it?
At least that's what i would do to be able to climb off the roof comfortably and without making too much noise.
But that might be only my nonstandard mind  

I know, conspiracy theories are easy to fall in love with, as i did when i was a teen and young adult.
In the end, when looking at things with a clear mind, which i also happen to have sometimes, mostly all of those theories tend to fall apart quickly.
Believing in them despite they didn't stand the reality check, or even if there is only resonable doubt involved, is not a sign of cleverness, to say it in a friendly way.

The real point here is (imho) online radicalization with a grain of gun laws.
But Trump, who is abusing the interweb for radicalization himself, is calling for death sence, is a little more than just irony, it's pure retardness.
Otherwise, we are speaking about a senile, grumpy Egomaniac here, which should be considered as well.

I trust the FBI in this. Or are there any real reasons not to?

BTW, in context to the mormon background of the shooter,

@Hueristic:
I originally said "good shot" about the 200m strike to the neck, assuming the assassin being not being a well trained shooter.
There are a few points i'd like ask you as a Marine, though:

1. Police special forces snipers (in my home country) are trained to aim for the small brain, because it takes down the victim without twitching a muscle, in case he/she is holding a gun or bomb trigger. That might be different in military tactics, where this is quite pointless.

2. How much does wind play into the precision of a 500 yard shot? How do you correct for it? Especially the direction. I assume that headwind and tailwind also have a slight effect on how much the projectile "falls" in a certain range, but that might be Millimeters. I also think that it depends a lot on the characteristics of the bullet and load/energy of the shell/powder used (speed and rotation of the projectile).