While the vast majority of persons interviewed had no explanation for the shooter’s actions, a review of electronic evidence or digital media that appeared to belong to the shooter, revealed that the shooter had a preoccupation with mass shootings, in particular the Columbine shootings and a strong interest in firearms. For example, there was a spreadsheet with mass murders over the years listing information about each shooting.
from Adam Lanza's "Obsession" With Columbine....
So, if the NSA is constantly monitoring everything for signs of terrorist intent, I think they have some 'splaining to do. But considering the reality of "the NSA" which really does have access to nearly everything on our online computers, it's not surprising that it would "overlook" signs of a mass shooting in the works, because the reality of "the NSA" which does this sort of thing (as opposed to the official NSA) is that it's the signals-intelligence division of organized Satanism, given special access to the internet and our operating systems, including the ability to hamper or deny us access to the internet at the ISP level. (The image above is a calling card they left on one of my Google blog "control panels.") Woodrow Wilson, in his famous 1913 quote about some mysterious, watchful force, was referring to organized Satanism. All that's changed in this regard are the tools at its disposal.
I suspect, although I cannot prove, that Sandy Hook shooter Lanza was driven by the Spirits of Darkness, which seem like the sort of being which would run organized Satanism. These beings can have very subtle effects, such as by simply planting a thought, a feeling, or urge in us. At worst, they can turn us into puppets, use us to commit some monstrous deed, and then have us commit suicide to keep us from talking about what was going through out minds. Those with weak will-power such as Lanza are the easiest prey. So, why would they use their "NSA" to report on themselves?