Another oddball scenario is that the Tsarnaev brothers were at the Boston Marathon with backpacks and not involved. Later when their pictures were published, they realized they would be caught for some other crime such as the Waltham murders.
They decided to make their epic run since they felt they would go out with glory. Then Dzhokhar took credit for the Boston Bombing in order to leave a memory with jihadis.
This theory has the following benefits.
- It explains why the Tsarnaevs did not leave the country after the bombing.
- It explains why they could not find how they made the bombs or who gave them to them.
- Why they only had one gun.
As a logical possibility, this theory helps focus attention on evidence that links the Tsarnaevs to the bombing itself and not just the chase or the note or confession.
What did we learn from the note or confession? Only things we already knew?
This is draft and preliminary. The above is hypotheses and speculation. Comments and corrections welcome. Please restate as questions. All other disclaimers apply.