There's more to the story than what the article is telling you.
Take a look at this article:
http://tvnz.co.nz/view/page/423466/481486
Not only was he on a methamphetamine known as "P" while committing the crimes, but he has been jailed 4 times and had 160 prior convictions, mostly for theft and burglary.
I would rush to judge this guy as mentally ill. It's likely that he's simply a bad guy pretending to be mentally ill to escape the consequences.
Some more good news: in September 2007, the Court of Appeal overturned Dixon's convictions and ordered a new trial. They say the new trial will likely be held this year.