The most likely candidates in my opinion…. (in order of most likely to least likely)
- Islamic terrorist.
- Occupy Wall Street wacko
- Right wing extremist
- Women's book club organizer
- Government conspiracy
Four possibilities that I can see:
1. Someone whose belief in a cause exceeds their regard for human life. I think we can agree that there are such people in the Tea Party, OWS, gun rights advocates, eco-terrorists, and all sorts of political or religious groups. Since the minimum number of people required to pull something like this off is one, I think they are all a possibility, though I doubt there's going to be a connection to a much larger group in any case.
2. A sociopath. Perhaps our mistake is seeing larger purpose where there is basically none. Perhaps this is a person who just likes to kill and to feel powerful.
3. An agent of a foreign state. We are in conflict with a number of countries to a greater or lesser degree. If North Korea or Iran had managed to get a loyal operative into the country, they would seem to have little reason to claim credit, for instance.
4. While I think if this were al Qaeda or some other religious/political/terror group, we'd have heard a claim of credit by now, else what would be the point for them, it is possible that they could be behind it.
My strongest candidate, and it really is based on very little, is a gun rights advocate, probably a militia member, with or without the blessing of the rest of the militia. The choice of a bomb, perhaps demonstrating that it is still possible to harm lots of people without guns, on the day that new background check legislation is gaining speed, seems suggestive, and the choice of doing it on tax day might align with a lot of these people politically. But this could really just be a Rorschach Test result.