But here's the part that gets me - they tell the guy they carjacked "we are the Marathon Bombers" - revealing their identity to a random stranger. And then, later that night, they just stop and let the guy go. The same guy they confessed to a few minutes ago. After murdering so many other random strangers. This strikes me as particularly peculiar, because why would you put the dogs on yourself if you were fleeing? Why wouldn't you have hurt or killed that guy too?
Warning: Pure speculations.
Here is my theory.
Most political terrorists want others to know why they committed the act.
They didn't just tell him that they were the bombers, but gave him their whole litany of grivences against the USA, and they let him live so he could be their "spokesman" explaining why they set the bombs. The victim recounted what he could recall so that the FBI could follow leads that such intel could provided. But has declined to act as their mouthpiece.
Author