juan zuarte, the president said today the investigation is in iten fancy but we know there was a pressure cooker involved, there may have been b.b.s involved, shrapnel and that maybe a circuit board was found that was used as a timer. what does this tell us about the source of this explosion? >> well, gwen, this is part of the forensic work that happens now and what authorities are looking for are signatures in the devices themselves that can give them some clues as to who may have been behind the attacks. what this tells us, at least to date, what we know is this was designed to have maximum effect. even though the explosive charge itself wasn't massive. it was designed with the ball bearings and nails and other shrapnel to have maximum impact upon explosion and so what that tells us is that this is more than the work of a mere amateur but it's certainly not sophisticated enough to tell us that it's the work of a bomb-making mastermind and so this, again, is helpful, it's probative, but it doesn't give authorities enough to determine if we're talking about a lone wolf actor or a down-siz