It is similar to Lanza and the guy who shot Gifford and the anti-war bomb in NYC and Eric Rudolph and Tim McVeigh except none of them were right-wing.
But a bunch of right wingers wanted to do it in their heart because Rush Limbaugh told them to do it.
It wouldn’t surprise me if they never find who did it because they are probably aware that the culprit would embarrass the White House.
I think it’s too early to jump to any such conclusions.
I also believe there are lots of hard-working and ethical people in LEO, and any such attempt at coverup would require the cooperation of hundreds of them, or more. I just don’t see it as particularly viable.