In July 2008 anthrax vaccine researcher Bruce Ivins committed suicide, leaving behind a grieving wife, two adult children, and scores of baffled friends and colleagues. According to the FBI the 62-year-old had murdered 5 people and sickened 17 others in the anthrax letter attacks of 2001.
By late 2005 FBI investigators, using sophisticated genomic analyses, had linked the letters to a single flask of Ames strain anthrax, a particularly virulent strain of the anthrax bacterium. Ivins, a researcher at the US Army’s Medical Research Institute for Infectious Diseases (USAMRIID) in Fort Detrick, Maryland, was the custodian of this particular flask, labeled RMR-1029.
Amex anthrax strain. Credit: CDC
Today, nine months after Ivins’ death and nearly eight years into an investigation that has consumed millions of dollars, some scientists and legislators are not convinced that the FBI’s case would have succeeded in court.
“Anything of this seriousness should be demonstrated beyond a reasonable doubt,” says US Representative Rush Holt, who in March renewed his call for a national commission to thoroughly investigate the anthrax letter attacks of 2001 and the government’s “bungled response” to the crime. “It raises the bar when the person [FBI investigators] have fingered isn’t alive to defend himself, requiring an even greater standard of proof. I don’t think they have met that standard.”
Holt is not the only one in Washington calling for a more thorough look at the FBI’s handiwork. Patrick Leahy, a Democractic senator from Vermont and a target of one of the anthrax letters, along with Senator Arlen Spector, a Republican from Pennsylvania, challenged the FBI’s conclusions at a Senate Judiciary Committee meeting in September 2008. Both said they doubt that Ivins, acting alone, could have carried out the crime.
That month the FBI formally petitioned the National Academy of Sciences (NAS) to form an independent panel of scientists to review the validity of the methods used to link the distinctive strain of anthrax in the letters with RMR-1029, and to provide expert opinions on other scientific questions related to the case.
In February at an American Society of Microbiology meeting in Baltimore, FBI researchers who had previously been bound by FBI confidentiality rules gave the first detailed scientific accounts of the case. “The science leads to the flask,” says Jacques Ravel, assistant professor of microbial genomics at the University of Maryland School of Medicine, who spoke at the meeting. “There is no other flask that has the same signature.” Ravel sequenced the genome of the anthrax in one of the letters and helped identify four distinctive mutations that ultimately led to the flask of RMR-1029.
Identifying the unique strain of Ames anthrax in the letters was only the first step. Investigators then had to develop and validate assays capable of pinpointing the mutations and screen thousands of blinded samples from academic and government laboratories.
At the February meeting FBI scientist Jason Bannon said that though many laboratories known to work with the Ames strain voluntarily surrendered samples, the FBI also conducted search and seizure operations to retrieve others. Of 1,072 samples from 18 labs, only eight samples contained all four of the mutations in the distinctive strain of anthrax in the letters, according to Bannon. One of those samples came directly from the flask of RMR-1029 and seven others were cultured from the spores in the flask. Only one of the eight cultures was not sourced to Fort Detrick. The FBI has not disclosed the identity of the eighth lab.
Ravel vigorously defends the rigor of the procedures the FBI imposed on participating laboratories as they worked to validate the genomic “fingerprint” that led investigators to RMR-1029. “It was almost insane, the precision of every step,” he says. “Nobody does it that way in a regular lab.”
Most critics dispute not the quality of the genomic science that led investigators to the flask of RMR-1029 but rather the conflation of Ivins with the flask. “There were other labs out there that were presumably sourced for RMR-1029,” says Gerard Andrews, Ivins’ former supervisor at USAMRIID. “What was the detective work that eliminated those labs?”
Most critics dispute not the quality of the genomic science that led investigators to the flask of RMR-1029 but rather the conflation of Ivins with the flask.
Skeptics also point to the mystery of a common bacterium called b.subtilis found in the attack spores but not in flask of RMR-1029. Anthrax-loaded letters sent to the New York Post and NBC News were heavily contaminated with subtilis, which must have been present in the media used to grow the spores, says Ravel, who sequenced the subtilis found in those letters.
Ravel’s team compared hundreds of blinded samples of subtilis provided by the FBI looking for a match for the letter subtilis. “We never found a match,” he says. “Not even close.” That fact, says Andrews, probably exonerates Ivins. “If it was a contaminant they would expect to find it all over Bruce’s lab. You should have been able to find it in the strain archives or in somebody’s freezer box at USAMRIID. It’s very significant that they didn’t find it. But that issue has been sort of pushed under the carpet because it doesn’t support their case.”
The FBI has asked the NAS to look into the subtilis contamination issue and other technical questions related to the investigation. But the FBI has not yet officially hired the NAS to appoint an investigatory panel, probably because of tight budgets, says William Kearney, deputy executive director of the office of news and public information at NAS. “We cannot appoint a committee,” he says, without a signed contract.
Meanwhile, Rep. Holt would like his proposed National Commission to look at “what happened, how and why it happened, and what we need to do to prevent any future occurrences.” His bill has some support, he says, though not enough to ensure passage. “It’s not high on the national agenda right now,” he says. “But it should be.”
Deborah Rudacille is a freelance science writer and the author of The Riddle of Gender and The Scalpel and the Butterfly: The War Between Animal Research and Animal Protection. Roots of Steel, a history of Baltimore steelworkers, will be published in 2010.
Originally published April 14, 2009