>> reporter: the sydney siege raises the specter once again of what the intelligence community calls lone wolf attacks, the most difficult to predict and stop. australian officials estimate at least 100 people in australia support jihadist groups in syria and iraq, providing money or assisting with travel for example. but intelligence chief david irvine said this in august. >> a recurring nightmare for me has been the so-called lone wolf, often radicalized over the internet and has managed to avoid coming across our radar. >> reporter: dozens have gone to fight in syria and iraq. among them, t...