It's not unusual for traumatic events to give rise to conspiracy theories of one sort or another, and so it has been with the Boston Marathon Bombing, though it seemed to take a bit longer for them to be generated than in some of the previous instances I can recall.
If we go back to the JFK Assassination in 1963 -- which I can still remember pretty well, and which seemed to have started the line of conspiracies and lies and government reformations, failures and breakdowns we've been subject to ever since -- we can see how easy it has been to induce the common people to believe something that simply may not be true. This goes for both the Official Story and the various alternative conspiracy theories as well.
Ever since then, I've been convinced that 1) the Official Story is a lie; 2) many, if not all, of the conspiracy theory alternatives to the Official Story originate from some of the same sources as the Official Story.
In other words, the conspiracy theories form part of the process by which most of the public is convinced of the "truth" of the Official Story while simultaneously providing those who are not convinced or convincible with plenty of distracting and generally false leads to consider and argue over indefinitely.
So it has been with the Boston Marathon Bombing, as it was with so many other traumatic events of the last several decades.
All we, the plebs, need to understand is that we are to live in persistent fear of arbitrary threats from sources we can't know or understand and we are to obey the commands of Our Betters -- for our own safety and security, of course.
This is the consistent message conveyed to us from on high: fear the unknown but always present threat; obey official orders (or, in the case of Boston's lockdown, what has been euphemistically and propagandistically called "requests to stay indoors.")
Seems to have worked pretty well...