ohmymimi re: your Joel Marshall tweets - from my regular reading of right sources, I can say this is correct. They believe Soros/Jews/the Left are funding AND directing the caravan as an election stunt.
The shooter, now - he was an anti-Semite, but he was also anti-Trump (according to them). He was a nationalist, and thought Trump a globalist. Trump lit the fire and kept it stoked however.