parties to commit violence against american lives. the thing you want to know is who the son saw, what he was thinking at the time. you want to understand his mind set and start to build a tree of associations. people he knew, people who influenced him and follow up with those people. >> the second question then would be how do you know what they say you can trust and what it is they can't? at the same time, sort of walking this fine line because here you have this mother and father despite any kind of lack of sympathy people here in boston would have for these parents potentially. they just, you know, lost one son, another son charged with what could be, you know, death penalty eligible crime. how do you handle that? >> well, clearly the parents are understandably overwrought. and you always pay attention to what anybody says and trust nothing that anyone says either until you can verify it. you take any person's comments