Less than a month after the September 11, 2001 attacks, letters containing spores of anthrax bacteria (Bacillus anthracis, or B. anthracis) were sent through the U.S. mail. Between October 4 and November 20, 2001, 22 individuals developed anthrax; 5 of the cases were fatal.

During its investigation of the anthrax mailings, the FBI worked with other federal agencies to coordinate and conduct scientific analyses of the anthrax letter spore powders, environmental samples, clinical samples, and samples collected from laboratories that might have been the source of the letter-associated spores. The agency relied on external experts, including some who had developed tests to differentiate among strains of B. anthracis. In 2008, seven years into the investigation, the FBI asked the National Research Council (NRC) of the National Academy of Sciences (NAS) to conduct an independent review of the scientific approaches used during the investigation of the 2001 B. anthracis mailings.

Review of the Scientific Approaches Used During the FBI's Investigation of the Anthrax Letters evaluates the scientific foundation for the techniques used by the FBI to determine whether these techniques met appropriate standards for scientific reliability and for use in forensic validation, and whether the FBI reached appropriate scientific conclusions from its use of these techniques. This report reviews and assesses scientific evidence considered in connection with the 2001 Bacillus anthracis mailings.

Contents

• THE NATIONAL ACADEMIES
• COMMITTEE ON REVIEW OF THE SCIENTIFIC APPROACHES USED DURING THE FBI’S INVESTIGATION OF THE 2001 BACILLUS ANTHRACIS MAILINGS
• BOARD ON LIFE SCIENCES
• COMMITTEE ON SCIENCE, TECHNOLOGY, AND LAW
• Preface
• Acknowledgments
• Summary
• 1. Introduction
  • 1.1 BACKGROUND
  • 1.2 CHRONOLOGY OF EVENTS OF FALL 2001
  • 1.3 BRIEF SUMMARY OF THE FBI’S SCIENTIFIC INVESTIGATION
  • 1.4 SUMMARY OF FBI AND DOJ SCIENTIFIC CONCLUSIONS
  • 1.5 COMMITTEE PROCESS
  • 1.6 ISSUES FOR CONSIDERATION IN READING THIS REPORT
  • 1.7 ORGANIZATION OF THE REPORT
• 2. Biology and History of Bacillus anthracis
  • 2.1 INTRODUCTION
  • 2.2 THE BIOLOGY OF B. ANTHRACIS
  • 2.3 CLINICAL ASPECTS OF ANTHRAX
  • 2.4 B. ANTHRACIS AS A BIOLOGICAL WEAPON
  • 2.5 PHYLOGENY OF B. ANTHRACIS
  • 2.6 THE EARLY HISTORY OF THE AMES STRAIN OF B. ANTHRACIS
  • 2.7 SUMMARY
• 3. Scientific Investigation in a Law Enforcement Case and Description and Timeline of the FBI Scientific Investigation
  • 3.1 INTRODUCTION
  • 3.2 SCIENCE AND SCIENTIFIC INVESTIGATION AS PART OF A LAW ENFORCEMENT INVESTIGATION
  • 3.3 THE FEDERAL COORDINATED RESPONSE AND ASSIGNMENT OF LABORATORY WORK
  • 3.4 COLLECTION AND ANALYSIS OF CLINICAL AND ENVIRONMENTAL SAMPLES AND CROSS CONTAMINATION
  • 3.5 COMMITTEE FINDINGS AND RECOMMENDATIONS
• 4. Physical and Chemical Analyses
  • 4.1 INTRODUCTION
  • 4.2 SPORE PREPARATION AND PURIFICATION
  • 4.3 SURROGATE PREPARATION AND PURIFICATION
  • 4.4 SIZE AND GRANULARITY OF THE MATERIAL IN THE LETTERS
  • 4.5 PRESENCE OF SILICON AND OTHER ELEMENTS IN THE LETTER MATERIAL
  • 4.6 FEATURES OF BACTERIAL GROWTH CONDITIONS AND PROCESSING METHODS: DETECTION OF MEGLUMINE AND DIATRIZOATE
  • 4.7 MEDIA COMPONENT ANALYSIS
  • 4.8 VOLATILE ORGANIC COMPOUNDS
  • 4.9 DETERMINING WHEN THE MATERIAL WAS PRODUCED: RADIOCARBON DATING OF B. ANTHRACIS SAMPLES
  • 4.10 STABLE ISOTOPE ANALYSIS
  • 4.11 COMMITTEE FINDINGS
• 5. Microbiological and Genetic Analyses of Material in the Letters
  • 5.1 INTRODUCTION
  • 5.2 IDENTIFICATION OF THE B. ANTHRACIS STRAIN
  • 5.3 WAS THE B. ANTHRACIS IN THE LETTERS GENETICALLY ENGINEERED?
  • 5.4 B. SUBTILIS CONTAMINATION OF THE NEW YORK SAMPLES
  • 5.5 IDENTIFICATION AND CHARACTERIZATION OF COLONY MORPHOLOGICAL VARIANTS IN THE EVIDENTIARY MATERIAL
  • 5.6 COMMITTEE FINDINGS
• 6. Comparison of the Material in the Letters with Samples in the FBI Repository
  • 6.1 INTRODUCTION
  • 6.2 CREATION OF THE FBI REPOSITORY (FBIR)
  • 6.3 USE OF THE GENETIC ASSAYS TO TEST FOR THE FOUR GENOTYPES
  • 6.4 DERIVATION OF RMR-1029 SPORES
  • 6.5 ANALYSES OF THE REPOSITORY SAMPLES AND STATISTICAL INTERPRETATION OF THE EVIDENCE
  • 6.6 ANALYSES BASED ON RESAMPLING OF RMR-1029 AND INTERPRETATION OF THE RESULTS
  • 6.7 COMMITTEE FINDINGS
• Bibliography
• Index of Documents Provided by the Federal Bureau of Investigation
• Appendix A Radiocarbon Dating
• Appendix B The Forensics Potential of Stable Isotope Analysis
• Appendix C Committee Evaluation of Statistical Analysis Report
• Appendix D Biographical Information of Committee and Staff

NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This study was supported by Contract No. A9N0902700 between the National Academy of Sciences and the U.S. Federal Bureau of Investigation. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the organizations or agencies that provided support for the project.