Ok, to follow up on who might possess a high calibre rifle either in their car/truck or in their home. There have been many very good scenarios suggested on here for various types of incident. Road rage was one, a festering resentment and anger which snapped was another, drug use was another. Please set aside the predator being after Jayme for a moment.
So a person or persons unknown who hunts in the Barron area, who routinely carries a high calibre rifle or can access one in their home, has an altercation with James Closs ; at work, on the road, or in his yard. Anger grows, the perp snaps and does his rambo attack on the front door. By the time he encounters Jayme his rage has dropped off and he cannot shoot her. So where does he/she go with Jayme? Answer, somewhere 4 minutes away on foot or 4 minutes away by car/truck, maybe back to their home in the local area. At 60 mph this could be up to 4 miles away. I am convinced it is a local responsible.