A significant number of scientists and biological warfare experts are expressing skepticism about the FBI's view that a single disgruntled American scientist prepared the spores and mailed the deadly anthrax letters that killed five people last year. These sources say that making a weaponized aerosol of such sophistication and virulence would require scientific knowledge, technical competence, access to expensive equipment and safety know-how that are probably beyond the capabilities of a lone individual. < snip > "In my opinion, there are maybe four or five people in the whole country who might be able to make this stuff, and I'm...