There are problems with all of the theories. If someone like the Russians wanted to stampede America into a panic they could have delivered enough envelopes to random persons to kill 500 people. The low number of envelopes suggests — or is meant to look like — an individual or small number of individuals. That plus the fact the attacks stopped argues for a “lone” perp, which incidentally puts paid to Greenwald’s conspiracy theory. It wasn’t Bush. It wasn’t the CIA, it was some individual.

There’s no reason to discount the possibility that al-Qaeda also had an anthrax program, but it doesn’t necessarily follow they delivered the attack. The fact that someone who shoots up a mall turns out to be a neo-Nazi doesn’t mean al-Qaeda doesn’t have the guns. We are really left with a lot of loose ends. The theories will multiply and lots of movies and books will be sold without any closure.