So I listened to the podcast and the Owl theory which I thought was ludicrous...but is it really. What got me thinking was her hair yanked from her head in both hands, I think around 15 strands or so each so not insignificant. I also read on owls and they definitely do attacked people and are very present in the area.
Then I imagined the scenario. They have sex, they have dinner, they watch a film. She then takes her valium (common for sleeping). He gets the wine out, gets her a glass, he mentions relaxing by the pool as weather is so mild. They go, she doesn't drink much if her wine as she has taken the valium. She starts feeling sleepy and says she's going to bed. She takes her glass, dump the wine in the sink and then hears some noise out if the front of the house. She goes out to investigate, sees one of her Xmas ornament down, goes to pick it up, the owl attacks.
She tries to get it off her head, hence the hair, and injuries on her elbows. She walks in, one hand in her head to work out extent of injury, opens door with other hand but then close with the other. She wants to check on her cut so goes up for flight if steps, runs up, slips, loses consciousness. She regains it, tries to get up and call Mike, she slips again, knocks her head again and is this time unconscious for longer. Hence the blood under her feet.
The issue that I've got with his guilt, is that although I do believe he had a motive of she found out about his affair and they had an argument is that the injuries don't really tally with being struck on the head (no brushing, swelling, fracture) nor falling down (7 injuries).