evidence listed, we don't even have charges at this point. but i'm curious to know if you would think right away that this now-dead alleged co-conspirator older brother might factor heavily into a defense of dzhokhar tsarnaev. >> yes, he very well could factor in terms of a defense of duress, in terms of a defense of knowledge. it's not clear at all at this point whether dzhokhar knew the ramifications of what he was doi doing, or knew what if anything was in the backpack that he was carrying. we don't know what his brother told him. we don't know what he agreed to. we don't know if he felt under pressure or threat from his brother or from others. all of these are open questions that will need to be explored.