About these purple "no trespassing" markings, can't this be used by someone to get away with murder? You drag someone inside the fence, you shoot him dead, and then claim he was trespassing and did not respond to verbal warnings and warning shots. How would the authorities in the relevant USA territories deal with this?
Shooting trespassers is not actually legal. However, the truth of the matter is that if you have any amount of land, you could make the body disappear and that would probably be that.