I grew up in Indianapolis, visited IU during my college years and have known many who have attended and graduated from there so have been naturally interested and following this case from the beginning.
I also have a cousin who currently goes to IU -- just finished his sophomore year. I've asked him a few times what, if anything he's heard - especially during this past school year. He referred to the group as a group of pretty privileged kids and hard partiers (no surprise to us, but was making the point that he's not really in those circles) and that most people have the theory that there was involvement from some sort of drug dealer.
I should say, however, that I heard this same theory first from a few friends who are attorneys in Indy (not criminal, but the community there isn't overly large). The chatter among lawyers involves the same theory -- some sort of dealer, low level or otherwise (not clear on these delineations) was involved. And that's the reason the body will never be found. In it of itself, this is no surprise, but that exact sentence "And that's the reason the body will never be found," is what stood out to me.
Naturally, that led me to fill in the details of someone with little to no emotional involvement in the situation, but with much to lose, criminally, if body found, was perhaps called in to take and dispose of LS. Wolf-style (Pulp Fiction reference). This thinking has me often returning back to the theory of the white truck and the fire near Martinsville combined with some rumors of pings from JR's phone to the Martinsville area.
There was some talk a page or two up the thread about how the really dark side of the drug trade, especially near a bigger market like a college campus, is never as far removed as we assume. That seemed like an important nuance to consider in this case.
Also, in combination with this theory, the speculation about ZO somehow being linked as a police informant at one time or another adds an even murkier layer, IMO, and makes some of the non-progress in this case make a bit more sense.