I was wondering if SJHD was maybe their supplier? They had to get the drugs from someone.
So, if he caused her disappearance, what happened? Just theorizing here...
Assuming the POIs' stories are true, and the last time she was seen was rounding the corner to go home, was SJHD waiting to grab her after she left 5N?
(Actually, I've wondered if JW could have done that. If the POIs are telling the truth. JW knew she was out with other guys, so maybe he was following/stalking her.)
Anyway I would think that if SJHD was also at 5N, and the other POIs know that HE caused LS's demise, the other POIs wouldn't have any problem ratting him out. Especially if he wasn't really a friend of theirs. He doesn't seem to fit the mold of the typical people they would hang out with - affluent families, etc. Why wouldn't the other POIs just all agree to blame him. "He gave LS bad drugs. We told her not to take them and that he was bad news." Three against one, whether that's really the way it went down or not.
I'm not putting too much emphasis on his shirt. My teenage SILs pick up shirts from random colleges at Goodwill and wear them.
I guess I still go back to the main POIs. They couldn't get their stories straight at first and how big of a jerk is a guy (JR) who doesn't walk a shoeless, phoneless, bruised, drunk girl home?
I agree about the shirt ... I thought Goodwill after the fact. Like you, I don't see him being in their friend group. Maybe a smalll-time supplier who they'd call on for help if things went south? Totally speculative, but being local he might know where to hide a body.
At this point, I still envision the POIs involved on some level, which probably doesn't fit his MO.
And I agree about JR. I've heard of a girl in my town who gave her cell phone to a guy who was walking home late at night without one. (My daughter called her the next day and got him.) Just saying.