I am blaming someone that called the cops.
I held my tongue on all the other thoughts on her, but an ANGRY woman is going to be the new phase of crimes like these. Just like the craigslist guy was bound to happen and the Yale killer was bound to happen and the Knox County and Witchita murders were bound to happen with the evolution of the American criminal.
Here's how that one plays out for me: (no evidence, just a theory)
Nancy gets a text during a party from JA's partner. JA sees said partner's phone. JA then approaches NC, who is drinking and could care less about the text because it meant nothing.
She then waits to "talk to her" and she blows her off. She fumes overnight.
The following morning, around 7, she stops by to talk to NC before NC comes by to paint (or whatever).
NC is in the garage grabbing something. She say hi and is very pleasant. JA gets angry because NC doesn't remember the text and it's implications. JA grabs her as she goes back into the house. NC doesn't expect it. She's dead in less than a minute. JA backs up the car and drops NC in the trunk and drives off, later dumping the body.
Around 2:00, she decides she needs to call the cops and place a little shadow of doubt on the situation and point towards the weirdo husband, because, being a weirdo husband, he will do the rest.
There is as much evidence to support my theory presented by the state at this point as they have presented against Brad Cooper.