From the NY Times
http://www.nytimes.com/2008/08/08/washington/08scientist.html
...Jeffrey Adamovicz, who was Dr. Ivins’s supervisor at the time, remembers the day the scientists opened that envelope, placed in a double-sealed bag inside a protective hood designed to deal with dangerous pathogens.
“The anthrax was floating around inside the bag,” Mr. Adamovicz said. “It was very scary.”
He said he turned to Dr. Ivins and said, “That stuff is amazing.”
“Yes, it is unbelievable,” he recalled Dr. Ivins replying. “I have never seen anything like that.”
....
He was particularly struck by the airborne nature of the deadly strain of anthrax found in the letters. Ellen Byrne, the wife of Dr. Byrne, remembers Dr. Ivins explaining how crafty the perpetrator had been to get the anthrax to be so finely ground that it was almost as light as air.
At a party, Dr. Ivins leaned over and, with his long, bony fingers, illustrated how the powder just sort of floated.
“He was just astonished,” Mrs. Byrne said. “Flabbergasted.”
“This was something that none of us ever dreamed of,” she remembered him saying. “It just could not be weighed. It could not be measured. It just hovered.”
Here's my 2 cents. Sounds like this anthrax was something unique and highly engineered, perhaps beyond the bounds of what this govt lab could achieve, perhaps not.
So Dr. Ivins may have tracked down and deducted which facilities had the capability to perform this minute and precise an engineering process. There couldn't be that many around the world, and as an expert in the field, Dr. Ivins may very well have followed one of Sherlock Holmes' maxims, and tracked down the source.
Remember a poster named BettyJo.
BioPort.
If Dr. Ivins had come up with a reasonable speculation as to where it came from, the who might have suggested itself.
At which point all he could do was off himself, naturally.
#62 Yes what is described in the NYT article has been confirmed
by other independent sources.
One prominent expert
(I forget who)
said the powdered anthrax floated like smoke.
They never had seen anything like that before.