By Allan Lengel and Joby Warrick
Washington Post Staff Writers
Monday, September 25, 2006
Five years after the anthrax attacks that killed five people, the FBI is now convinced that the lethal powder sent to the Senate was far less sophisticated than originally believed, widening the pool of possible suspects in a frustratingly slow investigation.
The finding, which resulted from countless scientific tests at numerous laboratories, appears to undermine the widely held belief that the attack was carried out by a government scientist or someone with access to a U.S. biodefense lab.
What was initially described as a near-military-grade biological weapon was ultimately found to have had a more ordinary pedigree, containing no additives and no signs of special processing to make the anthrax bacteria more deadly, law enforcement officials confirmed. In addition, the strain of anthrax used in the attacks has turned out to be more common than was initially believed, the officials said.
As a result, after a very public focus on government scientists as the likely source of the attacks, the FBI is today casting a far wider net, as investigators face the daunting prospect of an almost endless list of possible suspects in scores of countries around the globe.
"There is no significant signature in the powder that points to a domestic source," said one scientist who has extensively studied the tan, talc-like material that paralyzed much of Washington in the deadliest bioterrorism attack in U.S. history.
The FBI says it remains optimistic that it will find whoever killed five people -- two of them from the Washington area -- in a series of bioterrorism-by-mail attacks that rocked a nation still in shock from the Sept. 11 terrorist strikes. The bureau has assigned fresh leadership to the case -- Special Agent Ed Montooth -- and retains a full-time investigative force of 17 agents and 10 postal inspectors. "There is confidence the case will be solved," said Joseph Persichini Jr., acting assistant director in charge of the FBI's Washington field office.
The prevailing views about the anthrax powder, meanwhile, have been coalescing among a small group of scientists and FBI officials over several years but rarely have been discussed publicly. In interviews and a recently published scientific article, law enforcement authorities have acknowledged that much of the conventional wisdom about the attacks turned out to be wrong.
Specifically, law enforcement authorities have refuted the widely reported claim that the anthrax spores had been "weaponized" -- specially treated or processed to allow them to disperse more easily. They also have rejected reports that the powder was milled, or ground, to create finer particles that can penetrate deeply into the lungs. Such processing or additives might have suggested that the maker had access to the recipes of biological weapons made by the United States in the 1950s and 1960s.
In fact, the anthrax powder used in the 2001 attacks had no additives, writes Douglas J. Beecher, a scientist in the FBI laboratory's Hazardous Materials Response Unit, in an article in the science journal Applied and Environmental Microbiology.
"A widely circulated misconception is that the spores were produced using additives and sophisticated engineering supposedly akin to military weapons production," Beecher writes in the journal's August edition, in what is believed to be the most expansive public comment on the nature of the powder by any FBI official. "The idea is usually the basis for implying that the powders were inordinately dangerous compared to spores alone."
The FBI would not allow Beecher to be interviewed about his article. But other scientists familiar with the forensic investigation echoed his description. Whoever made the powder produced a deadly project of exceptional purity and quality -- up to a trillion spores per gram -- but used none of the tricks known to military bioweapons scientists to increase the lethality of the product. Officials stressed that the terrorist would have had to have considerable skills in microbiology and access to equipment.
"It wasn't weaponized. It was just nicely cleaned up," said one knowledgeable scientist who spoke on the condition he not be identified by name because the investigation is continuing. "Whoever did it was proud of their biology. They grew the spores, spun them down, cleaned up the debris. But there were no additives."
Moreover, scientists say, the particular strain of anthrax used in the attacks has turned to out to be a less significant clue than first believed. The highly virulent Ames strain was first isolated in the United States and was the basis for the anthrax weapons formerly created by the United States. The use of the Ames strain in the 2001 attack was initially seen as a strong clue linking the terrorist to the U.S. biodefense network.
But the more the FBI investigated, the more ubiquitous the Ames strain seemed, appearing in labs around the world including nations of the former Soviet Union.
"Ames was available in the Soviet Union," said former Soviet bioweapons scientist Sergei Popov, now a biodefense expert at George Mason University. "It could have come from anywhere in the world."
Many law enforcement officials believe that ever-improving technology eventually could lead to a break in the case. Ongoing tests could lead authorities to the lab where the anthrax originated -- something authorities have said for years could help close the case.
More traditional tactics are still being used: The FBI has conducted 9,100 interviews and issued 6,000 subpoenas in one of the most exhaustive and expensive investigations in the bureau's history. Authorities say investigators continue to have a number of specific individuals in their sights, describing the suspect list as "fluid."
One prevailing theory among investigators is that the attacks came from within the United States rather than from an overseas terrorist organization.
However, a law enforcement official said, "we have not closed the door on any possibilities. There's a discrete number of individuals who continue to be investigated, both internationally and domestically."
Over the years, officials have publicly identified only one "person of interest," and that was more than four years ago. Steven J. Hatfill, a former Army scientist, has denied wrongdoing and has never been charged. He is suing the Justice Department, alleging that officials leaked false information about him that caused great harm.
Law enforcement officials won't talk about Hatfill.
Homeland Security Secretary Michael Chertoff, in a meeting this month with Washington Post reporters and editors, would not say whether any single individual continues to draw special attention as a "person of interest."
"I'm not telling you that right now the bureau is focused on someone or not focused on someone," Chertoff said. "There are in my experience a lot of instances where we might know or have a good reason to believe who committed a criminal act, but we may not be able to prove it. So when you say something is not solved, you should not assume from the fact that there is no criminal prosecution we don't have a good idea of what we think happened."
Persichini, of the FBI's Washington office, acknowledged frustrations but said that "no one in the FBI has for a moment stopped thinking about the innocent victims of these attacks, nor has the effort to solve this case in any way been slowed.
"While not well known to the public, the scientific advances gained from this investigation are unprecedented and have greatly strengthened the government's ability to prepare for -- and prevent -- biological attacks in the future," Persichini said.
Nonetheless, failure to solve the mystery has bred public skepticism.
"If the FBI's investigation has become a cold case, then it's time for [FBI Director Robert S. Mueller III] to acknowledge that and take steps to deal with it," said Sen. Charles E. Grassley (R-Iowa), a frequent critic of the FBI. "I'm concerned that the FBI may have spent too much time focusing [on] one theory of what happened and too little effort on the other possibilities."
Staff writer Spencer S. Hsu and staff researcher Meg Smith contributed to this report.