Enjoyable, but too much of a stretch, plot-wise [SPOILERS INSIDE]

There is no way Joe gets away with it. The guy has had two GF disappear / die, at some point he becomes a suspect. I've watch enough Forensic Files to know. Everytime he used Benji's phone it would ping to his location. His finger prints were on the rock covered in blood that he hit Peaches with. That cop in CT could identify him. At some point Paco would realize what he saw and tell the cops. Benji's blood is still in that book box, you can't get rid of blood, it will always appear with luminol.