it is a way to connect dr. ivinsto that crime, to the location where the letters were mailed. >> narrator: at fbi headquarters, they had something they believed was even stronger- - they thought they had caught ivins intentionally misleading them about the alleged murder weapon, rmr-1029. >> it just showed us his willingness and deliberate attempt to mislead us, and actually tell us mistruths. >> narrator: the fbi had found matches between the anthrax in the letters and one particular source. >> samples start coming back positive. and all of those samples that turn out positive have all been drawn up originally from bruce ivins' 1029 flask. >> narrator: but the sample bruce ivins gave them from rmr- 1029 did not match. to investigators, it was proof ivins was trying to mislead them. >> this is the only one we know of that wasn't right, that didn't come back to what it was supposed to be. >> and so, they instantly began to wonder if this wasn't an attempt to obscure the fact that rmr-1029 was the source of the anthrax

question is, what physical container with the material have to be put in so hypothetically, someone of dr. ivins' gill could've had the envelopes with him and could have loaded the spores into the letters, sealed them with a tape. all the letters were sealed tightly with tape, put it in a ziploc agee and out. >> forgive me if this is false information but i did read that following the united states anthrax letter attack there were some, or there was a letter -- is that connected to bruce ivins attacks or is that completely false information? >> well there were a lot of letters that actually continue to be found around the country that were hoax letters. there was no other letter in any other part of the world that contained this unique batch of anthrax either mainstream after at -- like anthrax or certainly anthrax with spores derived from this unique flask of rmr1029. >> the people that have a letter sent to them laced with anthrax, why were they specifically targeted by bruce? >> that's a great question and i should point out that there were four letters that were recovered. it appears that th

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