http://www.sfgate.com/cgi- bin/article.cgi?file=/c/a/2001/10/09/MN203701.DTL&type=printable "Like all living things, anthrax bacteria evolve with subtle characteristics unique to each geographic area. Forensic biologists can trace those changes in bacterial DNA. If old stockpiles of Soviet-era anthrax were sold by rogue scientists to terrorists, genes could identify those as well. "