I agree, they're criminals and should be sent home. Please take note, I have absolutely no problem with people immigrating here legally.
The issue is that catching them and sending them back home obviously isn't working too well. Here's the real answer, start penalizing the people that are easier to find, the ones who are profiting off of their labor. If they couldn't get work, the problem would take care of itself. It'd be extremely easy to make fines and penalties for employing illegals so stiff that no one would ever weigh the risk against profit. Here's the big problem with that, the government usually does what big businesses want.