By Carrie Johnson and Joby Warrick
Washington Post Staff Writers
Tuesday, August 19, 2008
FBI officials attempted to bolster their case against researcher Bruce E. Ivins yesterday by presenting experts who said that a lone scientist working for three to seven days with readily available equipment could have produced the lethal spores used in the 2001 anthrax mailings.
Investigators reverse-engineered the deadly material sent to Senate offices and media organizations and concluded that a single person could have manufactured and dried it, said James P. Burans, director of the National Bioforensics Analysis Center.
Yet bureau officials and scientific experts acknowledged that they have not resolved all the intricacies of the bacterial powder that killed five people, sickened 17 and set off a national panic after it showed up in the U.S. mail at various locations along the East Coast after the Sept. 11 attacks.
"I don't think we're ever going to be able to put the suspicions to bed. There's always going to be a spore on the grassy knoll," said Vahid Majidi of the FBI Weapons of Mass Destruction Directorate.
Bureau officials took the extraordinary step of briefing reporters and editors of scholarly journals on what they called "a body of powerful evidence" in an attempt to eliminate misconceptions about their investigation. Prosecutors had homed in on Ivins, a longtime researcher at Fort Detrick, Md., before his suicide last month.
The scientists concluded that spores used in the mailings were not weaponized or coated with a special substance to make them more easily inhaled. The germs were traced back to a single flask at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), which exhibited four significant mutations that amounted to a genetic fingerprint.
Among the most persuasive pieces of evidence was the genetic analysis that the FBI says conclusively linked the letters to spores in Ivins's lab. Ivins possessed a flask of anthrax bacteria unlike any other -- a blend of spores from dozens of batches made in Army labs at Fort Detrick and at Dugway Proving Ground in Utah. Ivins's concoction -- labeled RMR-1029 -- was a mix of normal anthrax cells and four mutated varieties, or genetic oddballs.
The bacteria used in the attacks contained precisely the same mix of normal and mutated cells, the officials said. Of more than 1,000 samples of anthrax bacteria collected by the FBI in the years after the attacks, only eight contained the same four genetic mutants. All eight could be directly traced to the flask in Ivins's lab, the officials said.
While the FBI has acknowledged that more than 100 people could have had either access to Ivins's flask or samples of material from it, investigators say they eliminated all others as suspects.
Bureau scientists also found that Ivins had access to all the tools and skills needed to make the fine powder mailed to Senate offices in September 2001. Despite initial suspicions that the powder was weaponized, the process used to make the powder was relatively simple. FBI scientists easily reproduced it with gear that Ivins regularly used.
Anthrax spores that were simply cleaned and dried made an "extremely friable" powder that could disperse easily, Majidi said. "It would have been easy to do this at USAMRIID," he said.
The two-hour briefing did not silence speculation from scientists, lawyers and other critics who have tracked the government probe for years. In interviews with The Washington Post, Paul F. Kemp, an attorney for Ivins, disputed the government's statements. Kemp asserted that his client simply misunderstood the scope of prosecutors' requests for anthrax cultures in 2002, rather than trying to mislead them by sending questionable or phony samples.
The questions were compounded because the bureau destroyed Ivins's initial anthrax sample in 2002 after agents determined that it did not meet the standards investigators set out in a subpoena. An extra copy of that sample was preserved by Paul Keim, an expert at Northern Arizona University, who provided it to investigators when they asked for it four years later.
Government scientists also acknowledged yesterday that they could not figure out how to reproduce silicon that appeared inside the dry spores, making an exact match elusive.
Significant questions remain, including how the perpetrator managed to mail the letters on a busy Princeton, N.J., street while avoiding detection. Scientists, prosecutors, FBI agents and postal inspectors said yesterday they still could not determine exactly how the victims were exposed to the deadly germ. Investigators have never found the letter, sent to a Florida tabloid newspaper, that claimed the first victim, photo editor Robert Stevens.
It took years for government scientists, working with more than 60 outside consultants, to develop a way to trace the mutations in Bacillus anthracis and narrow their search to Ivins's flask. Investigators used circumstantial evidence, including late-night lab visits by Ivins and e-mail messages depicting his psychological turmoil, to further narrow in on him.
The FBI said it gathered 1,070 samples of anthrax bacteria from labs all over the world and only eight tested positive for the genetic markers. Those samples came from two institutions: USAMRIID and another they declined to identify.
The investigation continues even after Ivins's death. Investigators have yet to disclose what material, if any, they recovered from computers at a Frederick public library he visited hours after returning from a psychiatric facility in late July.