Was Ivins "suicided" instead of committing it?

He knew he was under investigation and was about to be arrested. The thing that I don't understand is what was HIS motive. I know the motive behind the anthrax attack judging from the intended victims but this is a scientist who would have known the danger of sending anthrax spores through the US mail. That really makes no sense to me at all. The fact that there was a letter in each envelope that warned the recipients to take antibiotics tells me that death was not the real intent. To me, that means there is a lot more to be determined.