I want to see his brothers interview, the one that is in law enforcement. I would expect because of his position he would feel obligated to cooperate in the interviews. Did he, or did he not?
When my family has Thanksgiving dinner, the rest of the family knows which of the other family members are coming, and if I arrive in my brother wasn't there, I would ask my mother when is he expected. What did his brother think of when his brother was supposed to be arriving versus him arriving? If he was coming for dinner for a family dinner, I would expect them all to arrive at about the same time.
And his brother arrived at about 2:30. If KB was expected, What story did his brother hear about the reasoning for that? Or when did he learn that he wasn't coming. PF called his mother at 4:24, two hours after his brother got there. Hmmmm
KB wasn't sure about whether she was going to do dinner that day, and that is why she wanted the recipe for a dip. So when he re-entered the condo at 1:24 p.m., was she expecting to go out to Cracker Barrel at that time, to go to Mom's house, or that it was going to be canceled completely?
I'm guessing the most plausible thing is that she was under the impression they were going to go somewhere, and he said you get ready and I will go shopping? (ETA and I'm recalling her mother saying that her hair up in the video at Safeway did not look like she was ready to go out, which I thought was a strange remark at the time)
I don't think the timeline allows for him to have killed her before he went to Walmart. It's too tight in my opinion.
ETA, also, wasn't the recipe that she wanted was for a dip in case going out was not going to be done. To make a dip sounds like something to take to somebody else's Thanksgiving dinner versus sitting around and eating a dip at home.