Genetic fingerprinting studies indicate that the anthrax spores mailed to Capitol Hill are identical to stocks of the deadly bacteria maintained by the U.S. Army since 1980, according to scientists familiar with the most recent tests.
Although many laboratories possess the Ames strain of anthrax involved in this fall's bioterrorist attacks, only five laboratories so far have been found to have spores with perfect genetic matches to those in the Senate letters, the scientists said. And all those labs can trace back their samples to a single U.S. military source: the U.S. Army Medical Research Institute of Infectious Disease (USAMRIID) at Fort Detrick, Md.
"That means the original source [of the terrorist material] had to have been USAMRIID," said one of the scientists.
Those matching samples are at Fort Detrick; the Dugway Proving Ground military research facility in Utah; a British military lab called Porton Down; and microbial depositories at Louisiana State University (LSU) and Northern Arizona University. Northern Arizona University received its sample from LSU, which received its sample from Porton Down. Dugway and Porton Down got their samples directly from USAMRIID.
In another development yesterday, government health officials said they planned to recommend that about 3,000 people who were exposed to anthrax, including hundreds of Washington postal and Capitol Hill workers, be offered an experimental vaccine as a precaution in case antibiotic treatment alone failed to protect them from getting sick.
The FBI's investigation into the anthrax attacks is increasingly focusing on whether U.S. government bioweapons research programs, including one conducted by the CIA, may have been the source of deadly anthrax powder sent through the mail, according to sources with knowledge of the probe. The results of the genetic tests strengthen that possibility. The FBI is focusing on a contractor that worked with the CIA, one source said.
But it remains unknown which lab may have lost control of the material that apparently ended up in terrorist hands. One of the two scientists familiar with the genetic testing, who has been advising the government on the anthrax scare, said investigators still know little about security at Porton Down, though they have no reason to suppose it has been inadequate. Of the domestic labs, Dugway has attracted the most attention from the FBI, he said.
Dugway is also the only facility known in recent years to have processed anthrax spores into the powdery form that is most easily inhaled.
Scientists have known for some time that bacteria used in the terrorist attacks belong to the Ames strain, a variant of the anthrax bacterium, Bacillus anthracis, that was first isolated from a cow in Iowa and has been under study by military scientists for decades. But the Ames strain comes in various subtypes that can be distinguished from one another by detailed tests on the microbe's genes.
The genetic fingerprinting finding was made by a research team led by geneticist Paul Keim at Northern Arizona University in Flagstaff, which has been comparing the Ames strain bacteria found in the Senate letters to other Ames strain samples retrieved from nature and from various university and government laboratories.
"That's good detective work in the sense of determining the origins; this will narrow the search for the people who had access to the strain," said Jennie Hunter-Cevera, a microbiologist and president of the University of Maryland Biotechnology Institute.
Other experts were cautious, noting that it is possible that the exact subtype of the Ames strain could have originated elsewhere -- perhaps even isolated from animals or soil in the wild.
"It's an important finding but it's not one of those things that says, 'Aha!' " said Richard Spertzel, a former director of the U.N. biological weapons team in Iraq.
The scientists are still planning to do genetic testing on anthrax bacteria from the Defense Research Establishment Suffield, a Canadian military research facility, the University of New Mexico in Albuquerque, and the Battelle Memorial Institute in Columbus, Ohio, a government contractor doing research on anthrax vaccines. Those are the only other facilities known to have received samples from USAMRIID.
The researchers also plan to test samples obtained from nature, and from other university labs known to have the Ames strain to see if any others match. But of the few such samples that have been tested so far none has matched the spores used by the terrorists. In addition, the researchers want to examine other characteristics of the samples, such as proteins, carbohydrates and other substances in the material.
"If there's also a telltale piece or trace of nutrients or chemicals that show the process, that's even better. You start adding the pieces and go from tentative to confirmative," Hunter-Cevera said.
The CIA's biowarfare program, which was designed to find ways to defend against bioterrorists, involved the use of small amounts of Ames strain, an agency spokesman said yesterday. The CIA declined to say where its Ames strain material came from. The spokesman said, however, that the CIA's anthrax was not milled into the volatile power form found in the letters and that none of it is missing.
Nevertheless, the FBI has turned its attention to learning more about the CIA's work with anthrax, which investigators were told about by the agency within the past few weeks, government officials said. The CIA has tried to develop defenses against a vaccine-resistant strain of anthrax reportedly developed by the Russians several years ago.
While the CIA has had small amounts of Ames strain anthrax in its labs to "compare and contrast with other strains," a spokesman said, the agency did not "grow, create or produce the Ames strain." The anthrax contained in the letters under investigation "absolutely did not" come from CIA labs, the spokesman said.
He also said that the FBI is fully aware of the CIA's work with anthrax and suggested investigators were satisfied with the information they had been provided. Law enforcement sources, however, said the FBI remains extremely interested in the CIA's work with anthrax, with one official calling it the best lead they have at this point. The sources said FBI investigators do not yet know much about the CIA program.
Both law enforcement and intelligence officials said the CIA is cooperating with the FBI probe.
Investigators are considering a wide range of possible motives for the anthrax attacks, including vengeance of some sort, profiteering by someone involved in the anthrax cleanup business, or perhaps an effort by someone to cast blame on Iraq, which has an extensive bioweapons arsenal. Whoever sent the letters could have a strong scientific background, officials said, but they also believe the material could have been stolen and mailed by someone without such expertise.
A law enforcement source said the FBI did not initially include the CIA on its list of labs working with anthrax because the agency was not among 91 labs registered with the federal Centers for Disease Control and Prevention to transfer anthrax specimens. But as investigators interviewed workers at those known labs, they learned of the CIA's work, and in the past few weeks posed questions about it to the agency.
CIA scientists worked with other government agencies and outside contractors in the defensive biowarfare program, the agency spokesman said. The agency said most of its defensive work involves simulants, not active biological agents.
"Everything we have done is appropriate and necessary and consistent with our treaty obligations," he said, adding that congressional oversight committees, along with the National Security Council staff, has been kept abreast of the CIA lab work. "One of our missions is to learn about potential biological warfare threats," he said, adding that research can involve "anthrax and other biological agents."
Staff writer Joby Warrick contributed to this report.