Sorting Out

As far as I know, I've never met an illegal immigrant. How would I recognize one? They come from all directions: North – Canadians; East – Europeans and Africans; South – Mexicans, Central Americans and South Americans; West – Asians, Orientals and Australians. They come in all sizes, shapes and colors: male, female, tall, short, heavy, slim, women, men, children, white, yellow, brown. I do know one thing: they are not here legally. Somehow, they violated our laws and borders to be here. I also know that some are murderers, as witnessed in the local newspapers recently. I'm also sure, as Donald Trump has said, that some are nice people. I wish the nice ones could become citizens and stay here to make a positive contribution, but nobody seems able to sort them out. Any ideas?