act of terrorism, the work of an international terrorist organization or a domestic-based group, or were isolated acts.
- B. The Investigation Prior to the Scientific Conclusions in 2007
- 1. Early investigation of the letters and envelopes
It took nearly a year before Amerithrax investigators identified the location from which the lethal anthrax letters were mailed. The four envelopes recovered from Capitol Hill, the New York Post, and NBC each contained a Trenton, New Jersey postmark, but investigators learned that 48 postal offices and 625 street mail collection boxes fed into the Trenton mail processing facility. Each one of those mailboxes had to be swabbed for the presence of anthrax contamination to identify the specific box from which the letters originated. FBI Laboratory and Field operational response personnel swabbed 621 mailboxes. Analysis of those swabbings allowed investigators to identify a heavily contaminated blue street-side box located across the street from the main entrance to Princeton University, at 10 Nassau Street, Princeton, New Jersey 08542. After several months of investigation, investigators concluded in August 2002 that this was the box from which all of the attack letters were mailed.
Meanwhile, the four recovered anthrax letters and envelopes were subjected to a multitude of forensic analyses by the FBI Laboratory, the FBI Critical Incident Response Group, and the USPIS Forensic Laboratory. Ink samples from the handwritten addresses on the front of the envelopes were analyzed via solubility testing and thin-layer chromatography. These techniques confirmed that the type of pen or writing instrument used for the envelopes mailed to Brokaw and the New York Post was likely the same, but different from the writing instrument used for the envelopes mailed to Senators Daschle and Leahy, which also matched each other. None of the envelopes exhibited indented writing, watermarks, hair, or latent fingerprints. All envelopes were sealed with moisture activation of the manufacturer adhesive and reinforced with strips of transparent tape, both along the closure strip and the folds of the envelopes. Five to nine pieces of tape were affixed to each of the four envelopes.
Fibers were also collected from the envelopes. Eight different types of fibers were either affixed to the tape or found on or in three of the four envelopes; however, none of the fibers matched each other. In addition, none of the fibers matched any of the items of clothing or other fabric collected during any of the searches. A minute quantity of human DNA was detected on the envelope mailed to Senator Leahy, but laboratory analysis revealed that this DNA was inadvertently contributed by the FBI Laboratory technician who conducted the initial DNA analysis. The FBI Behavioral Analysis Unit (“BAU”) found that “there is a high probability, bordering on certainty, that the letters and envelopes were authored by the same person” based on the observed linguistic similarities among the letters.
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