Conversation so far:
who was the anthrax hoax victim?
Miller opened an anthrax hoax letter mailed to her New York Times office.
then what happened?
The 2001 anthrax attacks had begun occurring in the wake of the September 11 attacks in 2001.
what more is known about the attack?
anthrax-laced letters sent to ABC News, CBS News, NBC News, and the New York Post, all in New York City.
did these attacks result in any serious mishap?
Twenty-two people were infected; five died.
any interesting information in this section?
In 2008, the government's investigation of these mailings focused on Bruce Ivins.

Question: what was the result of this investigation?
Self-contained rewrite: What was the result of the investigation of the 2001 anthrax hoax attack?