meters or so between each other, that's kind of a behavioral profiling technique. if i were walking with you down the street someplace and we were talking and walking side by side, that would not arouse suspicion. but the way these people were walking should arouse sus speci suspicion. they are trailing each other. someone with a bird's eye view of this thing would say that's out of the ordinary, that's unusual. that's the type of thing when people do behavior profiling and profiling has become a bad word but when you do behavioral profiling, that's the type of thing that we train people to look for and so law enforcement can focus in on those folks. >> jeff, i appreciate you joining us. thank you. here in boston tonight, so many people are facing pain. they are facing tremendous challenges ahead. i want you to know that our thoughts are with everyone hurting tonight. we wish you strength and comfort. president obama spoke about the bombing victims and survivors at today's memorial in boston.