From what I have seen, it looks to me like this was done by someone other than the brothers who were arrested/killed for doing it. I think they were set up, either being sent there for some other purpose, or told to be there for something else.
The bomb was set off right where the people from Sandy Hook were standing, and I think there was a significance to that, but I have no idea how it related , but I believe it did.
Also, soon after the Boston bombing, there was a bomb/explosion at a fertilizer plant in Texas, and earlier that week, the Ft.Hood bomb squad was called out for another pressure cooker bomb in that same area.
The strangest part is that there is always some kind of a government drill for the exact same thing happening nearby, whenever o me of these disasters happens.
When the American spirit was in its youth, the language of America was different: Liberty, sir, was the primary object.