Researchers may have way to track source of anthrax

WASHINGTON -- Scientists analyzing anthrax have found tiny differences that might help identify the source of the bacteria used in the fall attacks.

Three months after anthrax hit Capitol Hill, senators and staff returned Tuesday to the nine-story Senate Hart Office Building, home to half of the 100 senators and closed since an anthrax-laden letter was opened there Oct. 17.

In the investigation, scientists hope that identifying genetic markers will allow them to trace the anthrax used in the attacks to one of about a dozen labs that held samples of the commonly held Ames strain.

Until now, no differences among the various anthrax samples had been pinpointed. But scientists at the Institute for Genetic Research in Rockville, Md., now say there appear to be a few subtle genetic variations between two anthrax samples they are comparing: anthrax used in the Florida attack and anthrax held by a British biodefense lab that originally received its sample from the U.S. Army lab at Fort Detrick, Md.

The differences still must be verified, a process now under way by researchers at Northern Arizona University, said Timothy D. Read, who heads the Institute for Genetic Research's effort to map anthrax's genes. But this could lead to a break in the investigation, he said.

A law enforcement official confirmed Tuesday that the findings have potential but cautioned that it is unknown whether they will lead to a break in the case.

"We're cautiously optimistic," the official said, speaking on condition of anonymity.