Are you aware of Boarder Patrol? Yeah how's that going ?The wall isn't a total solution, but it would prevent, deter how the majority of illegals cross the border. Seeing as how only 10% of crimes in Mexico are reported, i'd say there's a better chance he has a long history of criminal behavior, he just didn't decide hmm think ill start with border crossing, then try murder.
Are you aware of the US Coast Guard, the FAA?