WASHINGTON — In a break for anthrax investigators, scientists say they have discovered genetic fingerprints that may help determine which of many laboratories is the likely source of the virulent microbe used in the attacks.
The advance is a byproduct of a scientific effort to decode the full DNA or genome of the Ames strain of anthrax, the type used in tainted letters that began circulating through the mail last fall, killing five people.
Scientists at the Institute for Genomic Research in Rockville, Md., a private group working for the federal government, say they have found a small number of genetic differences between the preparation used in the Florida attack and a standard source of Ames strain anthrax.
To the frustration of investigators, conventional methods of genetic fingerprinting have so far failed to distinguish among the various stocks of Ames anthrax possessed by the different laboratories.
The new points of difference, which the institute's scientists expect to be verified in the next two weeks, could allow federal investigators to match the attack anthrax to one of the Ames samples they have collected from a dozen or so laboratories here and abroad, and thus perhaps identify where the perpetrator obtained the germs.
The genetic analysis of anthrax stocks "might give us the edge" in cracking the case, said a senior law enforcement official, speaking on condition of anonymity. He cautioned that the work was not finished and its value so far unknown. "It may potentially have some good yield for us," he said in an interview.
Scientists have never before compared two full genomes of an organism at every unit of its DNA, nor done so as part of a criminal investigation, the institute scientists say. The tool could prove important for law enforcement and fighting terrorism, shedding light on subtle relationships among germs that otherwise appear identical.
Meanwhile, workers were making final preparations for the reopening of the Hart Senate office building, three months after it was closed when a letter containing anthrax spores was opened there.
The nine-story building, home to offices of half the 100 senators, was to formally reopen at noon when Senate Majority Tom Daschle, D-S.D., and Environmental Protection Agency Administrator Christie Whitman planned to enter it together.
Hart has been closed since Oct. 17, two days after the anthrax-bearing letter was opened in Daschle's office. Following repeated delays, the 1 million-square-foot building was declared safe last week after several attempts to decontaminate it with chlorine dioxide, a toxic gas.
The building's reopening marks a major step in Congress' return to normalcy following a tumultuous autumn.
The Capitol was evacuated Sept. 11 during the terrorist attacks on New York and Washington and two days later because of a bomb scare. In addition, all six of the major House and Senate office buildings were closed for at least short periods while investigators searched for — and sometimes found — more anthrax.
Last week, an EPA spokeswoman disclosed that the anthrax cleanup in Hart and other congressional buildings cost an estimated $14 million through December.
Contributing: Associated Press