Its origins pointed to one conclusion: that only the government scientist could be behind the 2001 attacks. Federal investigators cinched their case against alleged anthrax mailer Bruce E. Ivins after sophisticated genetic tests by a California firm helped them trace a signature mixture of anthrax spores, the Los Angeles Times has learned. Well before the deadly 2001 anthrax mailings, Ivins, through his work as a government scientist, had combined anthrax spores obtained from at least one outside laboratory, people familiar with the evidence said. With the help of leading outside geneticists and a fresh look at the evidence by a...