If you want to commit such a major crime, you must first work up a scapegoat.
If Ivins did it, he failed to provide any scapegoat.
Someone else may have taken the Anthrax, from several labs, or even gotten it from Ivins and other scientists, using some ‘excuse’.
Someone else may have even garnered Ivins support for ‘teaching the media and the dam politicians a lesson’.
This someone may have been an anarchist, or a terrorist.
Knowing they’ll blame it on the guy that has some personal quirks, or addiction problems, would be the real seller.
There was an attempt - via a letter- to pin it on an Egyptian working at the lab during the Hatfill hubbub.