To start; I believe he killed her- I have read the autopsy and her scalp was ripped right down to her skull. I simply don't believe that can happen when you fall a couple of feet onto a soon curve.
However the timing and logistics of how he killed her do confuse me. The thought process of MP of I'm going to kill my wife and stage it as a fall down the stairs must have had to happen so quick as she would have had to have been in that position at the foot of the stairs. Now my theory is they were mid argument, she went to walk upstairs after saying she was leaving him, he grabbed the blow poke and beat her to death. Or he was blocking the stairs whilst she was at the foot of it, he smashed her head against the wall, she stood up (which is when she got blood on her feet) and he finished the job with the blow poke
All this is speculation of course but I would encourage anyone to read the autopsy. It makes the case all the more confusing- she was covered in bruises on the front of her face and her elbows and arms- I have no idea how that could have happened
I think the blow poke is a red herring. I think this is a man that has figured out how to kill someone simply by using a staircase. I know the evidence doesn't support it, but I think he killed both women. I think he was trying to prevent information known about him by these women from getting out. He's a narcissistic sadistic man and it tracks that he would adopt the children of a woman he murdered simply to throw suspicion off of himself. If the authorities would have been more competent, there would be fewer questions of his guilt