All four of the recovered anthrax envelopes contained a white, photocopied letter on paper cut to irregular size by trimming one to three edges of the page. The letters to the New York Post and Brokaw contain identical handwritten text, and the letters to Senators Daschle and Leahy likewise contain the same handprinted text. Three “trash marks,” or copy imperfections, of forensic value were found on the letters to Senators Daschle and Leahy, but not on the letters to the New York Post and Brokaw. These trash markings were compared to letters maintained in the FBI Anonymous Threat Letter File and to 1,014 photocopier exemplar sets collected from copy machines located inside or near the vicinity of every known biological laboratory that possessed virulent Ames anthrax in 2001. No matches were found.
- 2. Preliminary scientific testing of the Bacillus anthracis spore powder
The anthrax powder used in the attacks was forensically examined. At the outset of the investigation, three panels comprised of 33 of the nation’s leading authorities in bioweapons development from the former offensive bioweapons program, microbiology, chemistry, and microscopy were convened to assist the FBI in developing a comprehensive analytical framework to evaluate the anthrax powders recovered from the envelopes and the contamination found in the AMI Building. Twenty-nine government, university, and commercial laboratories assisted the FBI in implementing the panels’ recommendations. Consistent with these recommendations, scientists analyzed the anthrax powder contained in the envelopes utilizing many different techniques, including the following:
- Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Light Microscopy (LM), and High Resolution SEM/Energy-Dispersive X-Ray Microanalysis (EDX) to identify spore size, spore shape, spore quality, and the spacial profile of elements within the spore;
- Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) to provide information regarding the elemental composition of the anthrax spore powders from the letters;
- Gas Chromatography Mass Spectrometry (GC/MS) to characterize the anthrax spore powders with regard to the presence of agar (a growth medium);
- Accelerator Mass Spectrometry to identify the relative age of the material using C12/C14 isotope ratios; and
- Stable Isotope Ratio Analysis to provide information potentially probative of geographic attribution.
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