That's an interesting article.
It's too early for us to have an expert opinion on his mental state but I think it's worth looking at the characteristics of a sociopath. The term covers a range of social detachment characteristics, ranging from misanthrope to psychopath. Perhaps this killer's profile is somewhere within the profile of sociopaths.
Take a look at this:
http://www.mcafee.cc/Bin/sb.html
We in the US are not allowed to use the word 'psychopath' it has a negative connotation so we call it 'antisocial personality disorder' even though it is not exactly the same thing. It was taken out of the DSM and most psychologist will diagnose antisocial personality disorder.