Buckle up, because this theory gets a little wild. Despite much of the evidence pointing toward Michael beating his wife with a blunt object on the head and then pushing her down the stairs, a new idea emerged in late 2009: the lacerations on her head could be explained by an owl attack. Durham attorney T. Lawrence Pollard, who lived near the Petersons, came up with the theory when it was revealed that microscopic owl feathers and slivers of tree bark had been found tangled up in a clump of hair found in Kathleen's left hand.
Fans of the theory argue that the wounds on her scalp were consistent with marks that would've been left by owl talons, and the feathers were the kind found on owl feet. Needles from a cedar tree were also found on her body, and there were drops of her blood on the home's front walkway and the front door, suggesting that she could've fallen after being attacked outside the house, and then made her way inside. There had also been a number of owl attacks in the area around that time.
The owl theory was definitely an interesting one, but it wasn't strong enough to warrant a motion for a new trial. As for why it's basically ignored in The Staircase documentary?
"The purpose of the film was to follow the legal process," Jean-Xavier de Lestrade told Vulture in an interview. "If there would have been another trial, I'm sure that the owl theory would have been examined inside the courtroom. But because it was never introduced inside the courtroom, I decided not to talk about that theory. It's really a mystery, the way she died."