The Science Behind The 'Anthrax Letter' Attack Investigation

Scientists directly involved in the investigation of the anthrax letter attacks of 2001 described the process of investigating the anthrax letter attacks in a presentation given on February 24, 2009 at the ASM Biodefense and Emerging Diseases Research Meeting in Baltimore, MD.

Paul Keim of Northern Arizona University described the crime scene, the events, letters and the victims in the context of their work. Much of Dr. Keim's talk was about the Ames strain, which was the type of B. anthracis found in the letters. Scientists examined B. anthracis strains. Whole genome sequencing of the Ames genome led to the discovery of DNA polymorphisms that were unique to the Ames laboratory strain. Highly sensitive and specific assays were developed to identify the strain material. These were subjected to extensive validation to insure that the investigators knew their strengths and weaknesses.

Joe Michael from the Sandia National Lab in Albuquerque presented spore analysis – in particular he discussed the electromagnetic analysis for silicon in the spores. His analysis explained where the silicon is found within the letter spores and that its origin was probably part of the culture and growth process.

Jacques Ravel of University of Maryland School of Medicine/Institute for Genome Sciences, Baltimore, Maryland, presented the discovery of colony morphology mutants in the letter material and how these morphs were isolated and then whole genome sequenced. He and his team used comparative genomics to identify the genetic basis of the morphological differences. Finally, he presented their assay development, validation and implementation.

Tom Reynolds of Commonwealth Biotechnologies, Inc., Richmond, Virginia, described his team's development of two assays to detect the genetic signatures associated with the morphological variants from the letters. This included a description of the forensic analysis standards that were applied to the work.

Jason Bannan of the Federal Bureau of Investigation coordinated the scientific investigation of multiple laboratories and handled the evidence in the case. He discussed integrating the science from multiple labs and how it tied the anthrax letters to a particular source flask. He included a discussion of the federal legal standards for new scientific evidence and how the scientific teams were addressing this requirement.