I thought for sure I'd heard that the letter(s) sent to American Media in Florida were mailed before 9-11. I, also, heard somewhere that before Stevens was properly diagnosed with anthrax, someone else in another state had tested positive and was treated with Cipro, and that Stevens died unneccesarily because the prior incident was kept hush hush to avoid public panic.
I am not certain, though. I could be wrong and don't remember my sources.
I don't believe they ever found the source of the Florida anthrax. There were lots of false leads but I don't think the actual source was found. Just a little contamination in the mailroom and on the computer keyboard of the guy who died.
Maybe someone who remembers the facts better can correct that.
In any event, the October 9 letter attack was quite different. It was a much more serious attack using more refined anthrax. It may have been a copycat crime to the Florida attack and from an entirely different person.