that whole saga was so fascinating. the culprit ended up (likely) being one of the scientists involved, with the motive of justifying funding into anthrax research. because of the incredibly low mutation rate of anthrax, they couldn't identify the strain by DNA testing.

they had to do new science to fingerprint strains based on the quantities of different populations in the samples vs. the bottles - an investigation the culprit himself was involved in. as they uncovered the flask responsible and the very limited number of people who could get their hands on it, the attacker killed himself.