say a prayer. >> questions the whole nation is aski asking. why would the tsarnaev brothers do it? how did they do it, and most importantly who might have helped them? >> what they want to do is ensure that there are no other ties to any other groups that might try to follow up with this or plan something. >> julia kyyem is a former assistant secretary to homestand security. >> the other piece is building a strong case and making sure that case doesn't fall apart. that's why the indictment released this week was very, very careful to say, look, we know he used weapons of mass destruction. we know he killed people, and that's enough to give him the