Investigators were quite sure that the pre-meditated anthrax attacks in the United States in 2001 had the imprint of superior military quality anthrax; further investigations revealed that the anthrax used, belonged to the common variety, though lethal all the same. The FBI has since increased their probe into the source of anthrax that reportedly killed five people in the US in Oct 2001, weeks after the September 11 twin tower disaster.
The Anthrax which claimed the life of five people in The US was received by mail, which had also rendered 17 persons sick. Due to the attack, the whole of US was on tenterhooks, especially since the attack had occurred weeks after the Sept 11 tragedy.
Initially, the suspects were thought to be the scientists in touch with US Defence Laboratories. Despite the attack, no body was charged. Now, it has become clear that, though the anthrax spores were not of military quality, yet they still were of very high quality and extremely potent with no additives, arousing the curiosity of the investigators to trace its origin.