Guys:
Let's not forget that Friday was an "I Hate Brad" day. (per the previous testimony)
There were aspects of this that could have looked (to him, IMHO) that he was being jerked around (by Nancy, if she were still alive).
He had been jerked around on the separation agreement and while that is standard practice, he didn't have any reason to know that.
These people were having affairs and apparently unhappy.
The cop car ride, etc. is different for a happy husband and wife versus a divorcing couple and him already having seen evidence of her planning on leaving, getting ready to leave, but being "stuck" with her still does not constitute planning her murder. I would answer their questions to help, but then...I would run through my whole mind of everything that had been going on and I personally (not Brad) would be thinking of my kids and how to A) shield and protect and B) continue to provide for them everything they knew. It doesn't take a rocket scientist to think he was going to be their A, #1 suspect.
And as per my usual disclaimer, I am not saying he did not do it. I am saying I am having trouble with 1st degree.