The border patrol folks need to set up row upon row of those blue dye packs that the banks put in the bags and have them triggered by some kind of pressure-release mechanism. Like a land mine, but instead of killing people it’ll Smurf them and make them a whole lot easier to apprehend and return, even days after they’ve crossed.
Photograph, fingerprint, DNA test if they have a minor with them, and immediately ship to Mexico City or further south. If the fingerprint check results in a known arrestable offence, chuck them in the slammer and prosecute, then deport after they’ve served their sentence.
Oh, and bill their home country for all expenses.
Down here on the border we have many protected wildlife species. The most legally protected specie here though is an illegal alien. They have far more rights than we do and lawyers provided instantly by “human rights” groups.
All we are legally allowed to do is observe them, and report them. Anything else can get you in huge legal trouble.
Sorry I missed that you said Border Patrol needs to use the dye packs. I misread and thought you meant people who live here. Border Patrol is pretty restricted what they can do too though.