BBM: I not 100% sure but I think this was premeditated. He may have called the police just so they don't suspect him??? Maybe he was thinking he could get away with it??? I really don't know but this is my guess. SW stabbed BB over 20 times and I'm assuming it was with a knife. He actually carried the knife with him to the spot where he killed BB. I think SW took the sleeping bag with him luring BB into "making out" in the sleeping bag, then went from there and tried to bury BB the best he could. I think he then freaked out realizing what he did, drove around a bit, made up a story (therefore the girlfriend, didn't know last name or where she lived). MOO!
Please do not take it as fact that SW called the police to report BB missing. The post you quoted is literally the only place Ive read that. By all other accounts, BBs parents reported him missing and BBs parents tracked down SW thru BBs texts or snapchats.