Terrorist Use of Biological Weapons - Deadly Cultures: Biological Weapons Since 1945 - page 299

than 400 members. Ultimately close to 200 were charged with serious
crimes, including more than 40 indicted for murder. To date, 12 senior
Aum members, including Asahara, have been convicted and sentenced
to death. The Aum was stripped of its religious status and declared bank-
ruptcy. Nevertheless, its members have reorganized as a new group,
Aleph, and may continue to pose a threat.
The 2001 US Anthrax Letter Attacks
In the fall of 2001, a series of letters containing Bacillus anthracis spores
was mailed to media and congressional offices on the East Coast of the
US. They resulted in at least 22 cases of anthrax—11 cutaneous and
11 inhalational. Five of the victims with inhalational disease died, and
those who recovered suffered serious long-term disability. None of the
victims with cutaneous disease died, but some suffered persistent dis-
ability. Thousands of people were put on prophylactic antibiotic therapy
(none of whom became symptomatic), additional thousands had their
lives disrupted, the US Congress shut down for several days, several fed-
eral buildings were closed for months to years because of persistent con-
tamination, and cleanup costs, still accumulating, have been immense.
Despite the largest and most complex criminal investigation ever, the
FBI has to date been unable to identify the perpetrator(s), and it is look-
ing increasingly as though the case will never be solved. Without know-
ing the identity and motivation of the perpetrator(s), it is not possible to
determine if these attacks were terrorist or criminal in nature, despite the
nearly universal application of the bioterrorist label to them. We do not
treat them in detail here, although in our conclusions we will draw some
lessons from them for the evaluation of the bioterrorist threat.
The anthrax spore preparations in the last two of the mailings, out of
probably five letters total, were of extraordinarily high quality 29 (earlier
spore preparations appear to have been less sophisticated). They con-
tained about 10 12 spores per gram, near the theoretical maximum, given
the approximately picogram weight of an individual spore. The particle
size was quite uniform, about 3 micrometers (each particle consisting of a
cluster of about two to six individual spores), and the preparation may
have been treated with silica to prevent electrostatic clumping. This is a
highly sophisticated method of spore preparation, widely thought to be