Cavalry
.338 Win Mag
While this may be true I have to think its more because of who the victim was like @GOPerfect has mentioned.It depends on the level of crime. Speeding across the border is not a federal crime. Speeding across three states being pursued by law enforcement after conducting a mass shooting can be. Planning a bombing, making the bomb, going to another state can become federal. Making it federal lessens the jurisdiction fights between states.
Last year that dude from Nevada rented a UHaul in Florida then drove it to Brooklyn and decided to drive over people there. That panned out as a State crime not Fed. One might speculate it was because of his mental state at the time, but the shooter in this event does not appear to be in a proper mental state either.