Psychopaths always believe they are smarter than everyone else, and I do believe AA is one. That's why he can appear charming if it's to his advantage, and why he angers quickly if he feels someone has displeased him.
This was a hideous premeditated crime carried out by an organized murderer who thought he was going to get away with it as all murderers think. However he is no different than many others when overestimating his own smarts. Instead he's rather typical in that aspect.
AA thought no one would ever believe he would burn his victim up right in his backyard.
He thought hiding or destroying his victim in plain sight would be the best way to destroy what he had done to his victim before murdering her.
Heck we have seen far more intelligent, and highly successful murderers than AA carryout their own heinous murders also thinking they were going to get away with it too. We've seen murderers who were NASA rocket scientist doctors, lawyers etc. and they all thought they weren't going to be caught.
Of course they are never as smart as they have convinced themselves they are, and that is the reason most are caught because of the mistakes they made.
Law abiding citizens are very thankful, IMO, that hideous murderers like AA do usually wind up making mistakes resulting in them being caught.
Jmho