Some of my thoughts on JP and this case:
He had to be making money somehow to be able to put gas in his car. We don't know if his father paid to keep the power on at the cabin, but that makes sense to me. And maybe Dad gave him money to keep him afloat while he "looked for a job." He also could have been breaking into homes to sell stuff, and of course, the possibility of dealing drugs. I think the drugs is a good possibility and the "friends" who came over were just people buying. He's known for being quiet, so not a social butterfly.
About the murders, LE said the parents were a barrier. I think he planned on killing them from the first. He never intended to just take Jayme, he WANTED to kill her parents. He probably hates his own parents. This might be why he lived apart from them when he had no visible means of support. Maybe they were afraid of him.
I don't think anything about this was random, before or after. He planned everything out as far as he was able to do. To go to the length of shaving his head, and of course, armed. It was noted that he previously had a shaved head. Was he committing crimes back then like B&E? I still think he may have broken into the Closs home before the crime, looked around, knew the layout of the house, maybe even saw pics of Jayme then. He would have been able to tell how many people were in the home and who they were. Then he watched them to find out their schedules. Of course, Jayme's schedule might have been posted on a calendar somewhere.
I also do not think this was in any way romantic idea that he was saving her from her parents and she would fall in love with him. That's just not how a guy like this thinks. He may have hated her for having parents who loved her. He wanted to destroy that and control her. And let her live at his whim.
MOO.