These murders are shocking for a host of reasons, but no aspect of the crimes is more disturbing than Lafferty’s complete and determined absence of remorse. How could an apparently sane, avowedly pious man kill a blameless woman and her baby so viciously, without the barest flicker of emotion? Whence did he derive the moral justification? What filled him such certitude? Any attempt to answer such questions must plumb those murky sectors of the heart and head that prompt most of us to believe in God — and compel an impassioned few, predictably, to carry that irrational belief to its logical end….
The Fundamentalist Religious Views That Inspired Ammon Bundy and His Militia to Occupy a Remote…
Jon Krakauer

As horrifying as it is, it is not surprising or unimaginable.

Psychology, Neurology, Neurochemistry/Biochemistry