He was also affiliated with an anti government group..."New Freedom"...which apparently is a right wing organization. 
He was also, as was the guy in Dallas, a veteran....we have ...after 15 or so years of pointless war...trained and conditioned a lot of people to shoot and kill...and weve glorified it...and "romanticized" it...how many movies and TV shows have you seen where a bunch of cops get shot as part of the story?....weve been conditioned to where the response to a  wrong is to fight back...to lash out...to stand your ground...never surrender and all that stuff....we eat up violence and then cry and blame and cower with fear when it actually occurs...

I'm sure that the guys motivations, etc. will come out over the next few days...and  there wont be one  reason  but a number of convergent factors...so don't get me wrong, I'm not trying to  hang this on the guy's race or politics or veteran status...but on one level this is a corner we painted ourselves into......