"Voicing doubts, Congress presses FBI on anthrax case; Despite scientist's death, Democrats say matter is open" by Scott Shane and Eric Lichtblau, New York Times News Service | September 7, 2008
WASHINGTON - Officials also acknowledged that they did not have a single, definitive piece of evidence indisputably proving that Ivins mailed the letters - no confession, no trace of his DNA on the letters, no security camera recording the mailings in Princeton, N.J.
But they said the case consisted of a powerfully persuasive accumulation of incriminating details. "Who had the means, motive, and opportunity?" said John Miller, assistant FBI director for public affairs.