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Scientific Sleuthing Untangled Anthrax Mailing Case
Federal investigators counted on scientific techniques that were inventive and often improvised to unravel the genetic “fingerprint” of anthrax from a series of 2001 mailings and eventually narrow their pool of possible culprits down to a single U.S. Army researcher, the New York Times reported today (see GSN, Aug. 19). Late last year, the search led the FBI to a flask of anthrax held by Bruce Ivins, a microbiologist with the U.S. Army Research Institute of Infectious Diseases at After American Media Inc. photo editor Bob Stevens became the first victim of the mailings, the FBI consulted biologist Paul Keim of Northern Arizona University and learned the anthrax used was from the Ames strain, the bacteria’s most potent known form. However, Keim could not determine what specific sample of the strain was used. The Institute for Genomic Research, or TIGR, was tapped and by early 2002 had recorded the sample’s entire genetic sequence. The team then learned of small differences between the genome and genetic material from another Ames strain sample. “The finding was very good news for the investigation by giving hope that molecular forensics might bear fruit but, if so, large numbers of samples would need to be analyzed,” said Claire Fraser-Liggett, who at the time headed the institute. The team’s initial optimism that it could genetically distinguish various samples was curtailed after it found the mailing sample’s genome perfectly matched to that of the “Had that task been assigned to someone less experienced, these [culture differences] might never have been seen or their significance never realized,” Fraser-Liggett said. The team cultivated mutated anthrax comprising roughly 1 percent of spores used in the attacks and then decoded seven mutated genomes over a period of two years. The FBI eventually determined that the mutated anthrax had been drawn from 35 cultures produced at the The very large amount of anthrax that was cultured, concentrated and combined to create the supply “guarantees you will see these mutants, and when you mix them together you will have a characteristic signature,” said Keim, of “That’s when the genetics caught up with the investigators,” a U.S. Justice Department prosecutor said (Nicholas Wade, New York Times, Aug. 21). Meanwhile, Senator Charles Grassley (R-Iowa) yesterday said the FBI has not responded to an Aug. 7 letter in which he demanded details on key concerns about the case that investigators have not addressed publicly, Salon reported. “I assume one of the reasons I haven't [received a reply] is because in the meantime, the FBI has consented to a hearing that Senator [Patrick Leahy (D-Vt.) is] having, and a hearing is one instrument of doing it. “At the time I wrote the letter, I didn't know whether there'd be a hearing or not, and I wanted to make sure, as one individual senator who's not chairman of the Judiciary Committee, that I would do my own oversight and get answers to questions,” he said. Grassley called for the Judiciary Committee to open the upcoming hearing to the public. Still, he said, “it would be my intent to get all that information out, either through the hearing, or through answers to my letters” (Glenn Greenwald, Salon, Aug. 20).
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