Thx ... I would rather think that Jessica died quickly ... I think we all would rather believe that. However, I'm not entirely convinced, especially since he spent months fantasizing about abducting someone (we know he tried in May 2012, and may also have tried in 2010). We also know that he had an obsession with pornograpy.
Here's a cutaway of the basement of the house. The house is a four level split, so the main floor is the living room, dining room and kitchen (front entrance to the house). Upstairs, there are three bedroom, the main bathroom, and possibly a 1/2 bath in the master bedroom. I've approximated the locations of stairs and doors. Going down one flight of stairs leads to the garage level. This is where there probably is another 1/2 bath. There must be a door connecting the garage to the house interior on this level. There is one more set of stairs going down. This is where the furnace and hot water tank would be, and perhaps also some of the swimming pool system. There is 625 square feet of living space in the basement, but officially only a small portion of that is developed. I think that it's possible that Austin had a bedroom in that basement, or that he spent time there. There is a small, 3 foot high door from that basement area to the crawl space, which is underneath the garage. The height of that space would be about 4 feet. It's possible that Austin had plastic sheeting on the ground in the crawl space.