Unless every single one of those books is a word for word restatement of the wikipedia page, there is information about sociopathy which is known, and yet I do not know it.
To be fair, I've read books hundreds of pages long which contained less information than a reasonably complete Wikipedia article. There's almost no limit to how much you can write about a limited data set if you're at all good at storytelling. This is truer than usual for pop science, and especially true for pop psychology.
That being said, and clusterfuck though it is, ASPD and related disorders are probably the most intensively studied cluster in personality-space -- the study of "criminal insanity" (from which there's a more or less direct line to the modern understanding of ASPD) considerably predates Freud. The DSM criteria are purely descriptive and probably don't describe a natural kind with any great precision, but volume of data is not going to be a problem here; can't say the same for interpretation, though.
Well now we're running into the same problem from the opposite direction. The volume of data possessed by humanity != the volume of data I possess.
I have consistently, over the course of my life, heard people describe sociopathy and related mental illnesses as being caused by a lack of empathy. This, intuitively, seems wrong, since that seems like a massively important brain function, that really ought to have a major and extremely visible effect on your thinking. Now, obviously it does have a serious impact (amoral behavior, etc), but it seems rather unlikely to me that someone like this really shouldn't be able to mask themselves as normal. (I'm also not sure why lack of empathy would make you want to dissect squirrels, but that seems like a side issue).
The upshot is that I'm seriously confused about what these mental disorders are, and how they work. Do these individuals have the ability to empathize but not sympathize? I'm not sure how that would work, but I'm not at all an expert on cognitive science. Is the standard explanation for these disorders just wrong? Are these people genuinely figuring out what humans care about by looking?
(As a side note, if it's the last one, has anyone considered getting a sociopath to work on FAI? Bringing someone who can't be trusted into an enterprise is a risky move, but if there genuinely are people in the world who have spent their entire lives practicing working out human emotions without feeling them...)