Noah talks with NPR's Melissa Block about the Federal Bureau of Investigation's arrest of two men on charges of possessing a dangerous biological agent. The FBI says it believes the substance is anthrax, but tests have not determined that. The FBI says the men, who were arrested in Henderson, Nevada, may have been preparing to test the agent. One of the men, Larry Wayne Harris, was once a member of the white supremacist group Aryan Nations. Last year, he was convicted of fraud after illegally obtaining a sample of the bubonic plague through the mail.