I agree that the CR, MB, JR, JW doesn't seem like a group likely to work together out of mutual admiration and respect. And if just 1 of them saw the opportunity to sell out the other 3 to save his own skin, he and his lawyer would likely be down at BPD HQ PDQ, singing like a skylark.
Rather a potential theory:
they all have equal skin in this case, in that if their involvement is fully revealed--while not rising to the level of kidnapping/murder--it is bad enough that selling out the others involves too much risk with little reward.
All 4's involvement similarly does not rise to that level (so cutting a deal with the prosecutors to narc on *(a) murder(s) is out of the question) but makes them equally culpable.
If I'm understanding the relationships correctly, JW (LS's bf at the time) and JR are friends/fraternity brothers? And CR and MB are roommates, and they live(d) a few places down the street from JR?
Sounds like CR was the impetus for LS going out that night.
CR and LS head out to to Kilroy's at the fashionably late hour of a quarter to 2 am? Only to leave a half hour or so later and consider returning to LS's Smallwoods apt.
They nix that plan, walk over to CR's place which he shares with the still wide awake MB (writing two papers at once, dawg!).
1.5 hours later, approx 4:30 AM, JR--a sorta neighbor but not a friend and possibly hostile to CR--reports the last known sighting of LS, at a corner near his place.
So...what happened in the intervening hour and a half, btw LS and CR arriving at CR and MB's place and JR's reported last seeing LS?
If you run with the theory that LS and CR were indulging in/seeking out some sort of illicit fun, then perhaps that's why they aborted returning to LS's place and instead went to CR and MB's place.
They arrive at CR and MB's and MB's paper writing activity has consumed much of their party stash. Maybe they had some left and partied a bit, but at some point, the well ran dry and they/she wanted/needed to re-up.
Couple of different directions it can go at this point but both rely on JR being the go to guy in this situation, whether for LS alone due to JW or whether JR's is and has been CR's connect and thus JR/friends beating CR and JR being banned from Smallwoods.
Regardless, let's say LS ends up going to JR's by herself to score some more. What happens then?
If JR's holding, good question.
If JR himself, as is often the case in these situations, is simply a go-between for the actual suppliers and his friends/neighbors as clients, JR contacts his guy and he and LS wait around for the dealer to deliver.
Or JR is unable to get anyone to deliver and so LS decides to call it a night?
or JR does get someone to deliver and then LS takes her share and tries to walk home but something happens, someone (maybe the dealer?) snatches her?
In any case, JR is obviously crucial in this case. I'd try to find out what involvement and with whom he had with the local narcotics trade and go from there.
Could well be a non-starter but it is a theory that could be worked and either validated or eliminated.