Panel Finds No Conclusive Evidence to Identify Source of 2001 Anthrax Attacks

Despite the FBI's conclusion that an Army scientist sent anthrax letters sent to Congress and the media in the weeks after the Sept. 11 attacks, a new report casts doubt on the bureau's findings.

After a lengthy review, the National Research Council said the source of the anthrax powder could not be definitively identified.

While evidence supports the FBI's contention that it came from Ft. Detrick, a U.S. Army installation outside Frederick, Md., a report by the NRC released Tuesday found that based on the science alone, no conclusion could be reached.

The report is a significant blow to the FBI's long-standing case against Army scientist Bruce Ivins, who died of a suspicious Tylenol overdose in 2008. The FBI claims Ivins acted alone when he allegedly mailed the anthrax spores to members of Congress and the media in the weeks after the Sept. 11 , 2001, terror attacks. Five people died as a result of the anthrax mailings.

Among the findings by the congressionally chartered committee released Tuesday:

  • The FBI correctly identified the dominant organism found in the letters as the Ames strain of B. anthracis.
  • Silicon was present in significant amounts in the anthrax used in the letters. But the committee and FBI agree that there is no evidence that the silicon had been added as a dispersant to "weaponize" the anthrax.
  • Spores in the mailed letters and in RMR-1029, a flask found at the U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID), share a number of genetic similarities consistent with the FBI finding that the spores in the letters were derived from RMR-1029. However, the committee found that other possible explanations for the similarities -- such as independent, parallel evolution -- were not definitively explored during the investigation.
  • Flask RMR-1029, identified by the U.S. Department of Justice as the "parent material" for the anthrax in the attack letters, was not the immediate source of spores used in the letters. As noted by the FBI, one or more derivative growth steps would have been required to produce the anthrax in the attack letters. Furthermore, the contents of the New York and Washington letters had different physical properties.
  • Although the FBI's scientific data provided leads as to the origin of anthrax spores in the letters, the committee found that the data did not rule out other possible sources. The committee recommended that realistic expectations and limitations regarding the use of forensic science need to be clearly communicated to the public.
  • Further development and validation of methods for analyzing environmental samples might have benefited this investigation and will be important in future investigations.

In a lengthy response, the FBI said the law enforcement agency and Postal Inspection Service devoted 600,000 investigator work hours to the case and assigned 17 Special Agents to a Task Force, along with 10 U.S. postal inspectors.

The investigation spanned six continents, involved more than 10,000 witness interviews, 80 searches, 26,000 e-mail reviews, and analyses of 4 million megabytes of computer memory. It resulted in the issuance of 5,750 grand jury subpoenas and used 29 government, university and commercial laboratories for scientific analyses.

"The committee's report reiterates what is and is not possible to establish through science alone in a criminal investigation of this magnitude. The committee's focus was on the more novel scientific approaches used in this investigation and did not review the traditional forensic methods and techniques employed or the significant body of evidence gathered through traditional law enforcement techniques," the FBI said, pointing to its "Amerithrax" website for people to review the findings.

"The committee also concluded that it is not possible to reach a definitive conclusion about the origins of the B. anthracis in the mailings based on the available scientific evidence alone. The FBI has long maintained that while science played a significant role, it was the totality of the investigative process that determined the outcome of the anthrax case. Although there have been great strides in forensic science over the years, rarely does science alone solve an investigation. The scientific findings in this case provided investigators with valuable investigative leads that led to the identification of the late Dr. Bruce Ivins as the perpetrator of the anthrax attacks.