My spidey profiling sense is making me think this guy killed others and it would be possible to link his crimes together because the MO is rather unique...leaving your own homemade necklace? A single stab wound, no sign of sexual assault? He left the body in a relatively public place and seemed to be confident he wouldn't be caught. He had no trouble getting her in the car either. I wonder if it was an older teen who knew her? I also get the feeling it was a local.