Arrest, try and convict him then shoot Anwar al-Awlaki in the head. Or whatever it is they used to do to traitors in the United States.
As to the results of al-Awlaki's latest atrocity by proxy, I blame the victim:
'He shouted at me "What was that for?" I think I stabbed him again. I think I did it twice. I tried to attack him again. People started to scream.'
He should have asked her if they could just talk about it. Worked out so well for Theo van Gogh and everyone else who is still not paying attention.