Eight of the shooters were charged with depriving the students of their civil rights, but were acquitted in a bench trial.
I'm not going to make an exhaustive list of all the terrible shit perpetrated by the US government and its agents. It would be too detrimental to my health. But you choosing to bury your head doesn't prove anything either, so I guess I have one up on you.
you would do well to note that this page links directly to an entire wikipedia entry for 'US War Crimes': https://en.wikipedia.org/wiki/United_States_war_crimes