Oh, so that's what that scene was about! I re-watched it now and it really is incredible. Screenshots of some of Greenwald's notes (they don't say much):
My gut says a majority, I believe that the war is truly inward. A flagging system wouldn't be too difficult. You could even flag people who aren't dead and yet haven't raised a flag in some time-frame (Unibomber). Statistical analysis, the data's all there. Set up keys that resemble the analyses's output. Find what you're looking for. Unfortunately, those keys are controllable. You'll always find people who fit a certain profile, you will always find who you're looking for. Unfortunately, you'll require some vagueness to ensure that the net you've cast doesn't have holes too large.
1- http://i.imgur.com/Xk3tefg.jpg
2- http://i.imgur.com/3C7sdIA.jpg
3- http://i.imgur.com/8FNhVfE.jpg