I live in the next town over. I've driven by the house several times and have seen Peterson coming out of our local Wholefoods a couple of years ago. He still lives in the area.
My two cents. I was open to the owl theory but have decided it doesn't add up for two reasons. If the owl caught her on the head outside then there would have been a fair amount of blood outside and on the way to the inside staircase itself . If the owl was inside then there would have been evidence of havoc, as it would have flapped and panicked to get outside, leaving feathers, blood and probably knocking stuff over.
I sincerely hope the truth comes out properly one day, for Kathleen and her daughter and sister. Also for Elizabeth Ratliff as I think he was involved in that too. I believe he is the father to at least of one Elizabeths's daughters , even though it is said that DNA tests have proven otherwise. They all look so alike. I think that would have given motive for Michael to have pushed Elizabeth down the stairs in Germany.
As an aside, both Michael's sons are highly sketchy characters. In fact, Clayton Peterson did time for setting pipe bombs in an administrative building at nearby Duke uni, where he was studying at the time.
A couple of years ago Michael Peterson self published a book called "Behind the Staircase." I got it out the library and it was then most self serving load of twaddle you could imagine. He likes to paint himself as a hero and I sensed he was completely titillated in prison by the attentions of male prisoners. I couldn't finish it.
I believe he did it. Poor Kathleen.