Isn’t registering when an illegal alien or ineligible felon a crime. Don’t they commit perjury? How about round up those thousands and offer them (1) agree to deport or (2) be prosecuted for the felony, go to jail, then get turned over to ICE and get deported?
Deportation is a temporary inconvenience at best, for most illegals, and that's ONLY if they get caught, and ONLY if the arresting authorities choose to follow the letter of the law.
Given that there are 40 million of them in our country, the chances of any one of them facing actual deportation are between slim and none.
If we really want to change their behavior, we have to make the penalties for illegal entry too gruesome to confront.
I suggest stiff prison sentences with no possibility for parole as a starting point.