Does free will really exist?

Being stuck in the hotel room in Mumbai yesterday, I watched a great documentary about the "Source of Evil" on DW-World, a TV channel for German speakers abroad. The show asks scientists if crime originates in the brain and some interesting answers come along:

"Using medical high tech, researchers believe they are now closing in on the source of violent tendencies in the brain. Modern brain research has raised disturbing issues. Apparently, to act deliberately and of our free will is a rare luxury, according to Gerhard Roth in Bremen, one of the leading scientists in the field. Is free will merely an illusion - a trick of the brain designed to make life more bearable?"

In the show one of the researchers showed MRI pictures of the brain activity of a test person, who was supposed to click on a mouse button at a time of his choice. The brain activity happened before the person clicked on the button, meaning that the brain already could have made a decision before the person intended to click on the button.

I believe these research results are just a small part of what is going on in the human brain. Still... if these results are true, I guess web analysis and criminal law has to be rewritten.