God protect the little girl. That's pretty tragic. But will a wall prevent someone that is this incentivized to come back? 15 times. And I don't think those 'bollard walls' would do to much to stop a chap like this.
We would probably do well to simply jail them here. The assumption of non prosecution would largely dissappear, and the fear of a lengthy US prison sentence would dry this shit up but quickly. Would be expensive, but hey, we already jail minorities at a disproportionate rate; let's just switch up the demographic. I'd rather see violent offenders and repeat offenders in jail, than low level drug offenders. We are reembracing private prisons again despite the progress we had made moving away from this model; let's lock the real bad hombres up. Fuck deportation.
A better option would be to enter in to a deal with some third world nation for housing the criminal immigrants, just like what the Australians did. If the illegal commits a crime in the US, then he will serve his jail time in Uganda or Nigeria.
Have you thought why third world countries need in their country have found refuge thousands of criminals? No amount of money will justify itself. Besides, all criminals tend to organize gangs, and this is a threat to the state.