I'll check and see if "attention to detail" is one of the symptoms of a sociopath. But i personally think he's just a dumb sociopath.
This is a long (with real big letters tho) series of articles explaining how a sociopath behaves and the different levels of sociopathy. It seems HKS is a worst case scenario sociopath:
http://www.hss.caltech.edu/~mcafee/Bin/sb.html
I'll go with dumb sociopath, also. I said 'attention to detail' because he was meticulous in recording events the way he wanted them perceived.
The photos of happy, healthy Daniel and the baby taken within such a small window of opportunity would be my primary example.