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Additional Forensic Investigation of 2001 Anthrax Attacks

By Amesh A. Adalja, MD, FACP, May 25, 2012

The FBI’s conclusion that USAMRIID scientist Dr. Bruce Ivins perpetrated the anthrax attacks of 2001 is largely built on an extensive microbial forensics investigation. That investigation linked the spores found in recovered letters to material contained in a flask labeled “RMR-1029” that was under Dr. Ivins’ control. According to the FBI’s analysis, RMR-1029 contained anthrax spores of the Ames variety, with specific genetic features consistent with the letter attack materials. The results of research by the Chemical, Biological, Radiological and Nuclear Sciences Unit of the FBI just published in the Journal of Forensic Scientists provide additional data about the attack material.1

Evidence Based on Spore Purification Compounds

During the Amerithrax investigation, it was discovered that some laboratories that possessed the Ames strain were purifying the spores using a product that contained meglumine and diatrizoate. From lab records, it was determined that the spores contained in RMR-1029 were similarly purified using these compounds. This information gave rise to the question of whether the attack materials were taken directly from RMR-1029. To answer this question, the FBI developed a detection method that employed liquid chromatography and mass spectrometry to determine the presence of these compounds.1 As expected, the FBI investigators did find that anthrax spores taken directly from RMR-1029 contained both meglumine and diatrizoate. However, no evidence of these compounds was found when the spores from the anthrax letters were analyzed using the same method.1

Source of Attack Material?

The major implication of this study, as the authors note, is “that the evidentiary spore material was not diverted directly from RMR-1029.”1 This fact means that if the anthrax spores used in the attack were taken from RMR-1029, their preparation would have required extra steps prior to mailing. That type of purification would have required specialized machinery and likely would have left traces of the material on machinery. No such material was found, though, and in a recently settled civil case in Florida, the U.S. Department of Justice acknowledged that the specialized machinery was not available at USAMRIID.2

 In the 2011 National Academy of Sciences report evaluating the FBI’s scientific conclusions in the Amerithrax case, this finding was cited in support of the report’s conclusion that “it is not possible to reach a definitive conclusion about the origin of the B. anthracis in the mailings based on the available scientific evidence alone.”3


  1. Swider C, Maguire K, Rickenbach M, et al. Trace detection of meglumine and diatrizoate from Bacillus spore samples using liquid chromatography/mass spectrometry. J Forensic Sci 2012; Accessed May 16, 2012.

  2. Justice Dept. takes on itself in probe of 2001 anthrax attacks. Washington Post. January 27, 2012.

  3. National Research Council. Review of the Scientific Approaches Used During the FBI's Investigation of the 2001 Anthrax Letters . Washington, DC: The National Academies Press; 2011.