Identifying the anthrax killer

The F.B.I. seems convinced that it has finally solved the long-festering case of who mailed the anthrax letters that killed five people in 2001. . . .

But there is no direct evidence of his guilt. No witness who saw him pouring powdered anthrax into envelopes. No anthrax spores in his house or cars. No confession to a colleague or in a suicide note. No physical evidence tying him to the site in Princeton, N.J., from which the letters are believed to have been mailed.