The committee recognized that forensic science is the application of scientific methods to matters of interest to the judicial system and must, therefore, consider the norms of both science and the law (NRC, 2009a, Chapter 3). The committee also recognized that sometimes pressing national interest or security concerns, such as those present during this investigation, demand that newly emerging methods be applied to the assessment of forensic evidence even before those methods have been widely adopted or validated by peer review in the forensic and scientific communities. It should be noted that future biological attacks will probably pose greater challenges than did this attack: the agent may be a member of a species with a more complex and poorly understood population structure, the agent may be genetically modified in a manner that further obscures its origin, or a sample of the attack material may not be readily available (as it was in this case). This last possibility may mean that environmental or clinical samples, with their inherent added challenges, will have greater importance in a future investigation.
National security concerns and the pressures of an ongoing criminal investigation may require that the collection of samples and their evaluation be carried out under circumstances of secrecy that limit the capacity of outside observers to assess the validity of the forensic interpretations. Such circumstances pose special challenges in which the optimal application and evaluation of scientific methods may in some instances run counter to security interests. The committee faced this tension between science and security in its deliberations.
In the end, the committee considered the facts and data of the scientific investigation, the reliability of the principles and methods used by the FBI, whether the principles and methods were applied appropriately to the facts, and the conclusions related to these efforts. The committee does not, however, offer a view on the guilt or innocence of any person(s) in connection with the 2001 B. anthracis mailings or any other B. anthracis incidents.
Based on its review of the materials provided, the committee developed the findings presented in this report. The report is organized to provide background on the scientific characteristics of B. anthracis (Chapter 2); describe and review the procedures used in the early stages of the investigation concerning the collection of evidence and its processing and preservation, as well as the creation of a repository of B. anthracis samples collected from around the world for comparative and investigative purposes (Chapter 3); review and assess the physicochemical analyses of the anthrax evidence (Chapter 4); review and assess the biological characteristics of the material in the letters (Chapter 5); and review and assess the analyses and results of the FBI’s comparison of the evidentiary material against the samples in the FBI Repository (Chapter 6). The committee’s findings, analysis, and recommendations can be found in Chapters 3 through 6.