ago, put information like date of birth, you know, over time if an analyst wants to look up whatever the u.s. government knows about someone that was vaguely suspicious years ago, they can go to the tide list. let's separate out a watch list and a list that simply is a compilation of identity information about suspected people. >> so then, with, let's say this tide list, which we knew tamerlan tsarnaev and his mother was on, what is the red flag let's say for anyone on the list what is the red flag for investigators to say something is not right here? >> i would say violence, something that suggests the person is about to commit a crime or contemplating committing a crime. you're asking the right question now, and we're three minutes into it. that's the problem with the conversation across america the past few days. the question is, even if this person's name were tripped and you went to talk to him what is he going to tell you? i'm going to visit my family. you're going to ask him maybe about what happened, the conversations when the fbi talked to him a while ago. he's going to say i visited my