It was the simplicity of it all that was so scary. Someone drops a letter in the mail, it disappears into the system, and there mingles with millions of others to spread its deadly spores. Five people died. Twenty-two were contaminated.
Anyone could get it, from well-known newsmen and politicians to elderly retirees. Anthrax didn't discriminate, and as we soon learned...the same person was behind it all.
"The tests to date have concluded that the strains are indistinguishable," Tom Ridge said Oct. 19, 2001.
"Should we be concerned about anthrax attacks in the future? Yes, we should," said FBI director Robert Mueller.
It's become a frustrating global quest for the bureau. Agents have fanned out over Asia and Africa in recent months. In the valleys of Afghanistan they heard someone had hidden the anthrax they sought. It wasn't there.
Earlier they drained a pond closer to home. Nothing. After 53,000 tips, and 5,000 subpoenas — zero.
Randall Murch, a former FBI lab manager, sympathizes.
"We have a situation where there is no smoking gun per se. There is no link, no direct link between the person and the event and the material used."
So, increasingly, the bureau likens this case to another that perplexed them. It took them 17 years to finally flush a disheveled Ted Kazynski out of the mountains and expose him as the Unabomber, they remind, but in the end they always get their man.
And what about this case? The answer is always the same:
"To the best of my knowledge. There are no suspects, no significant leads," said Murch.
And privately, FBI officials concede the chances for an arrest are getting slimmer by the day.