From what I can tell, both RL and DN became fodder for the media and online sleuthing communities, like this one.
RL was suspected for a variety of reasons, and none of them have made sense to me after that time. I have heard nothing about him protecting his property, like in this case:
https://en.m.wikipedia.org/wiki/Signal_Mountain_murders
DN seems a better suspect, IMO. Here, I think if the suspect was like DN, there would be some sort of rage and sexual aspect to it, given his history.
So two motives: 1) This is my land (RL) and 2) Rage/ lust killer (who knows who it could be).
There is a third option the girls were targeted by someone known to them who wanted to silence them. That seems unlikely to me, because of the picture on the bridge and voice being made so public.
So frustrating, and disappointing there are no leads I know of leading to justice.