Evidence Reveals Few Clues to Powder's Source

It is an intimidating task: Take a tiny organism, sent anonymously through the mail, and figure out how it was grown, dried and turned into a powder. Identify any chemical that might be mixed in. In fact, there might be more than one additive.

"It's the chemist's nightmare," said Alan Zelicoff, a government physician, physicist and weapon specialist.

But it is those details that might give investigators clues to who made or mailed the anthrax that has already killed three people. On Thursday, government officials acknowledged that teasing the evidence from the bacteria is proving tough.

Many scientists outside the government say there is little doubt that the bacteria were mixed with some kind of chemical to help them float easily through the air and into their victims' lungs. But federal officials said they had not identified the chemical and were not even sure it existed.

"Although we may see some things on the microscopic field that may look like foreign elements, we don't know that they're additives; we don't know what they are," said Maj. Gen. John Parker, commander of the U.S. Army Medical Research and Materiel Command at Ft. Detrick, Md. "We're continuing to do research to find out what they possibly could be. They're unknown to us at this present time."

Nor is it clear who made the anthrax. The United States, Russia and Iraq turned anthrax into weapons, using different methods to dry and process the material that would leave different telltale marks on the germs. But officials said that so far they have found no match to any foreign weapon program and are not even certain that the material came from another nation.

"I don't think I've seen any preliminary tests that drew any conclusions as to where it could or could not have been produced," said Thomas J. Ridge, director of the White House Office of Homeland Security.

Quality of Spores Alarms Some Experts

Even with only incomplete data available, weapon experts outside the government say they are increasingly alarmed by the high quality of the anthrax preparation mailed to one location, the office of Senate Majority Leader Tom Daschle (D-S.D.).

Ridge described the anthrax spores sent to Daschle as "pure" and smaller than those sent in other letters. With enough of that bacteria, experts say, a person who distributed it covertly in a subway, shopping mall or other enclosed area would probably cause a large number of deaths.

"I think you would have to consider it potentially capable of massive casualties, though that depends on how much material they have," said Philip Hanna, an assistant professor of microbiology and immunology who studies anthrax at the University of Michigan Medical School.

"If they have a manufacturing capability, that is extremely worrisome," said Jonathan Tucker, a former United Nations weapon inspector now with the Monterey Institute of International Studies. It would be possible to "disseminate it, at least in an enclosed space, to inflict significant casualties."

Said Zelicoff: "For the first time in my 12 years of working in this arcane area, I'm scared."

Scientists have studied the bacteria under microscopes, including an electron microscope, which offers extraordinarily fine detail. They are also running chemical analyses. Zelicoff, who works on nonproliferation initiatives at the government's Sandia National Laboratories in New Mexico, said he presumed that scientists were also studying the bacteria in special aerosol chambers to determine how they move under different environmental conditions.

Scientists have also studied the behavior of the bacteria when faced with different drugs, as well as its genetic makeup. They have determined that the bacteria have not been genetically engineered to be immune to antibiotics. They have also determined that the bacteria came from the same strain, or family--a fact that is turning out to have little investigative value, Ridge said. Known as the Ames strain, it is found in laboratories around the world and cannot be linked to one source.

However, there are important differences in the bacteria found in different locations. The anthrax spores--the hardy casing containing the bacteria--found in Daschle's office were uniformly small, Ridge said, "therefore, they're more dangerous because they can be more easily absorbed in a person's respiratory system."

By contrast, the spores found at the New York Post were "more coarse and less concentrated," Ridge said. Samples taken from Florida and NBC in New York were too meager for scientists to study, he said.

Ridge and other officials did not comment on why anthrax with different qualities turned up in different places.

Richard Spertzel, a microbiologist who led the United Nations inspections of Iraqi biological weapon programs, said the differences in the bacteria might be a hallmark of Osama bin Laden's Al Qaeda network, known for establishing semiautonomous cells of terrorists who sometimes work independently toward the same goal.

Spertzel said it was possible that several Al Qaeda groups had been directed to mail anthrax to prominent figures a few days after the Sept. 11 hijacking attacks. One group might have obtained a sophisticated form of anthrax from a nation or scientist trained by a weapon program, he theorized, but another group might have grown or obtained lower-quality material. A third, he said, might have obtained no anthrax and instead mailed the powder that turned up at, among other places, the main office of the New York Times.

Success of Probe Still in Question

There is no guarantee that science can point investigators to whoever sent the anthrax or even narrow the field in a meaningful way. Even if scientists can determine what machinery was used to dry and process the bacteria and what chemicals were added, those materials may be widely available to laboratory workers in any number of industries.

Investigators are sure to try to match characteristics of the anthrax bacteria with what is known about anthrax used in the U.S., Iraq and former Soviet Union weapon programs. Those three nations are thought to have made the most progress in turning anthrax into a weapon.

But U.S. knowledge of foreign programs is incomplete. United Nations inspectors studied the Iraqi biological weapon program in the 1990s, but they did not gain complete knowledge of the program and have not been in the country since 1998. The former Soviet program was massive and produced a variety of lethal agents. U.S. officials probably don't have samples of all of them, several weapon experts said.

"I don't think we know in detail what the Chinese did. I'm not even sure we know with detail what the South Africans did," said Charles Duelfer, former deputy chairman of the U.N. Special Commission on Iraq, which ran the weapon inspections in that country. "Iraq could have done a lot of things, and other countries could have, that we don't know about."

"You can't rule out that there was Russian assistance or maybe assistance by a [rogue] Russian scientist, even if it turns out that any additives in the bacteria point away from Russia," said Spertzel, who nonetheless believes that Iraq likely supplied materials or know-how to whoever mailed the bacteria.

In the end, he said, science may have little to offer investigators. "I don't believe the science side of this is going to be able to say a certain organization or laboratory or person did it," he said. "It may narrow the field. . . . But I believe the connection is going to be made on intelligence, not on science."

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Times staff writers Ronald Brownstein, Faye Fiore, Janet Hook, Eric Lichtblau and Josh Meyer contributed to this report.