Snipped.
In my armchair assessment, SW was passive-aggressive more than he was a narcissist. He's so passive-aggressive that he kills his family, but only because forced into it by his wife killing the children (so he says).
She praises him a lot, which in my observation, is the go-to method in dealing with a PA person. Any criticism sets a passive-aggressive person off and they don't stop until you apologize for whatever fault/mistake that was theirs....so it's easier just to praise them, even falsely. It's the PA person's way of controlling the spouse - the spouse can't do anything that will upset the PA and gets in the habit of praising just to keep the peace.
She tells him what to do and is "bossy." I can see a PA wanting their partner like this because then all blame when anything goes wrong (like money problems) can then be placed on the bossy spouse.
I do see him as lacking empathy, but I think that's PA driven. I don't think of him as full of himself like a narc, and even though he's a liar, it's almost as if he does want to get caught rather than thinking he wouldn't get caught. When a PA is caught, it's always someone else's fault....it's even the friend's fault that SW couldn't finish covering up the murders, not the fact he did a terrible job with the cover-up.
Jmopinion, from my armchair