The evidence linking anthrax that killed five people in a series of 2001 letters to a flask of the spores in the laboratory of federal scientist Bruce Ivins was not as definitive as the Federal Bureau of Investigation claimed, a panel of researchers said Tuesday. Although the panel gathered by the National Research Council said it had no reason to believe that Ivins was not the perpetrator of the terrorist act, it faulted the FBI's conclusions that the perpetrator must have had a high level of skill to produce the powdered spores and that the spores must have come from Ivins' lab.
"We find the scientific evidence to be consistent with their [the FBI's] conclusions, but not as definitive as stated," panel chairman Alice P. Gast, president of Lehigh University said at a news conference.
Ivins died of what appeared to be an intentional overdose of Tylenol in 2008 as the government prepared to indict him for sending out the letters. He had denied involvement in the attacks to the end, and his lawyers continued to deny that he played any role in mailing the letters.
The five people who died in the mailings included two postal workers in Washington, D.C., a hospital employee in New York, a Florida photo editor and a 94-year-old woman in Oxford, Conn. Seventeen others were sickened, and postal facilities, the Capitol Building and some office buildings had to be shut down to clear them of the deadly substance.
The FBI concluded that the anthrax spores originated in a flask labeled RMR-1029 in Ivins' laboratory in Ft. Detrick, Md., and that the perpetrator required a high degree of skill, such as that possessed by Ivins, to prepare the powder for mailing and dispersal.
The NRC report, "Review of the Scientific Approaches Used During the FBI's Investigation of the Anthrax Letters," agreed that the anthrax in Ivins' lab was the dominant strain in the letters but noted that there were genetic differences in the materials in the New York and Washington letters, suggesting that it had been cultured elsewhere before being mailed.
The group also suggested that the genetic similarities could be the result of parallel evolution and concluded that the similarities did not rule out other sources.
The committee noted that silicon was present in the samples but that there was no evidence it had been added to the spores in an attempt to weaponize them — that is, to make them disperse more readily.
The panel also concluded that a high degree of technical skill was not required to prepare the samples that were used in the letters and that they were, in fact, a relatively crude preparation.
The panel also noted that the FBI had tried to investigate a potential Al Qaeda link to the mailings by attempting to grow anthrax from swabs taken from unspecified overseas sites but was unable to get the samples to grow.
