The way I see it is, Avery is not the brightest person. Somehow he managed to removed ALL his DNA and her blood from the crime scene, yet left visible blood in her car? He would have to be a mastermind to be able to remove all that blood, but yet he left her key on his bedroom floor, to be found in clear sight around the fourth time they searched the house? I don't know, as I've never hidden a murder, but if I put in so much effort to clean every little space on this whole big property,
why would I leave her phone and other id in my fire pit?
I guess i can't possibly see how it could have happened as the police described it. No way they raped this woman, slashed her throat, shot her, and there is no blood anywhere. Not on the mattress, walls, floor?
Maybe he could have done it, but not in the way they are saying.
Lastly I feel partially bad for his nephew. It's quite apparent he would say anything he thought they wanted to hear.
Just my opinion.