As John is returning from his journey into the woods to bury Emily, he removes his gloves as he's getting out of Emily's car and then touches the door handle... leaving his finger prints ON the door handle.
It takes much longer than many people realize to strangle someone. John let go of Emily's neck a few seconds after her eyes closed. She'd have only passed out at that point and left alone, would have regained consciousness within a short time.
Tommie-Amber Pirie's debut.