Powder used in anthrax attacks 'not routine'

Whoever concocted the wispy white powder used in last fall's anthrax attacks followed a recipe markedly different from the ones commonly used by scientists in the United States or any other country known to have biological weapons, law enforcement sources said Monday.

Extensive lab tests of the anthrax powder have revealed new details about how the powder was made, including the identity of a chemical used to coat the trillions of microscopic spores to keep them from clumping together. Sources close to the investigation declined to name the chemical but said its presence was something of a surprise.

The powder's formulation "was not routine," said one law enforcement official, who spoke on the condition of anonymity. "Somebody had to have special knowledge and experience to do this," the official said.

The finding, one of several emerging from months of intensive laboratory analyses of anthrax spores mailed to Senate offices in October, appears to further deepen the mystery of who is behind the worst act of biological terrorism in U.S. history.

The FBI has long suspected the attack was the work of a domestic scientist -- possibly someone formerly associated with the U.S. biological defense program or one of its contractors. But the discovery of the chemical suggests the culprit did not merely ape techniques developed by U.S. defense scientists or those used in other countries with known biological weapons programs, such as the former Soviet Union or Iraq.