NC may well have exaggerated things, but when she showed up dead in the ditch beside the cul-de-sac, that was making a bit too much of a play for attention, don't you think?
If she did not commit suicide, then someone else killed her. I take that as a fact at this point. If someone killed her, then someone is guilty. True, we have not seen concrete proof that it was BC, and while I am leaning that way, I am not at 100% yet. Statistically, most people who wind up murdered are killed by someone they know. So, you start there with the investigation, and see where it leads you.
Even if you are completely in the SODDI camp, you have to admit that if you were an investigator, and found the victim was not getting along with the spouse, then when you start checking things out, you see that there was a lot of stressors like infidelity, finances, pending divorce you would be derelict in your duty if you did not pay very close attention to that. Not exclusively, but Lo, you start finding evidence, things that don't add up, feelings and impressions that you and others notice. Pretty soon, like it or not, you have a suspect.