And...
CE has to be involved somehow beyond just knowing about it or helping RF eliminate evidence. If he unknowingly stepped into some ***** by helping RF, he would have told LE everything he knew by know. Why would anyone (narcissistic or not) be that protective of a friend if they weren't involved?
I'm sure LE has looked into their past phone records. Right?! How often did they call each other at 3am? How frequently did the communicate prior to 10/12? My gut says there was some type of drug involved and RF got it from CE. Whether it was intended to be lethal or not, it was (due to rage side effect on RF's part or OD on Zuzu's part)... and RF called CE after to tell him what happened. If it wasn't going to implicate him, CE could have just said, "sorry bro, you're on your own here." But instead, he gave him a ride somewhere, drove around with him somewhere, went to his friend's house and acted pretty stressed out, etc.
All the puzzle pieces are coming together and they're both going to have to start answering some questions. Hopefully, now that the remains have been found, CE will "remember" a few more things.