During its tenure, the Task Force generally was staffed by 25 to 30 full-time investigators from the FBI and the USPIS, as well as prosecutors from the United States Attorney’s Office for the District of Columbia. The investigators scrutinized more than 1,000 individuals as possible suspects, located both at home and abroad. The investigation benefitted significantly from the assistance and cooperation of 29 government, university, and commercial laboratories, which augmented FBI Laboratory efforts to develop the physical, chemical, genetic, and forensic profiles of the anthrax spores, letters and envelopes used in the attacks.
In the early years of the investigation, the Task Force did not know whether the letters were a state-sponsored act of terrorism, the work of an international terrorist organization or a domestic-based group, or were isolated acts. Much of the early efforts focused on attempting to classify genetically the spores used in the mailings and to track the envelopes and the letters used to their source. These investigative initiatives took considerable time, as genetic laboratory tests needed to be developed and validated, and traditional forensic means of examination of the letters were significantly hampered by the fact that these items were contaminated by anthrax spores.
At the same time, investigators were culling through lists of possible suspects, based on likely profiles including: scientific ability, laboratory access to the Ames strain of Bacillus anthracis, proximity and other links to Princeton, NJ (from which the letters were mailed), suspicious behavior, tips from the public and the scientific community, and possible motivation or incentive to commit such a crime. Task Force agents conducted interviews, and examined business records and publicly available corporate information, such as Securities and Exchange Commission filings, to identify any business that may have been motivated to commit the anthrax attacks for financial gain. The Task Force also launched initiatives to examine industries – such as the bio-pharmaceutical, bio-pesticide and agricultural/veterinary industries – for possible suspects, given their areas of expertise and the equipment they utilized. After thorough investigation using traditional law enforcement techniques, virtually all of the identified individuals were eventually ruled out.
In 2007, after several years of scientific developments and advanced genetic testing coordinated by the FBI Laboratory, the Task Force determined that the spores in the letters were derived from a single spore-batch of Ames strain anthrax called “RMR-1029.” RMR-1029 had been created and maintained by Dr. Bruce E. Ivins at USAMRIID. This was a groundbreaking development in the investigation. It allowed the investigators to reduce drastically the number of possible suspects, because only a very limited number of individuals had ever had access to this specific spore preparation that was housed at USAMRIID. The Task Force then began applying traditional law enforcement techniques to a very limited universe.
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