I haven't bought into the motive that DE wanted to silence Nicole, and the more I think about it, the even less I believe that was the case.
If he really wanted to silence her, he wouldn't have been so sloppy in leaving a trail. I know criminals can be dumb, but if his GOAL was to hide a secret, I really think he would've been more...well, secretive or perhaps stage it to cast blame far away from him.
He did absolutely nothing to distance himself from the crime. Everything led straight to him, from the SM contact to dumping her body near where his relatives live. I don't think he was motivated to kill her to keep her quiet.
I am leaning more and more toward thrill kill. They wanted to destroy. Perhaps at first it started out as SM taunting and humiliation, but it turned into a desire to humiliate "in real life" and then, finally, to kill. I think Nicole was targeted as an easy, convenient victim - and she wasn't a victim because she was going to expose DE. She was a victim because she was chosen by the murders to be their victim.
JMOpinion at the moment.
I still agree with the possibility of a thrill kill.
The way you worded what you wrote about silencing Nicole made me ponder that option a bit more from a different angle. What you're describing led you *away* from thinking 'silencing', but it actually makes me think it more. However it looks to me like you're thinking premeditated silencing, and I'm now seeing elements of panic in what he did.
He was indeed sloppy and left a trail, dumped Nicole's body near familiar terrain (I imagine DE exploring that area as a younger boy on family visits), didn't seem to cover anything up. That could be cold-bloodedness, or panic, IMO.
I don't know if I actually believe this is what happened, but I can see it possible: they didn't plan to kill Nicole that night. Yes, they planned to kill her, but not that night - someday later. When DE picked Nicole up, she said something to him that freaked him out - something about disclosing their relationship (not out of malice, but because she was so happy). That went on for a bit, possibly an argument, and he ended up killing her in a panic (possibly figuring the plan was put together far enough to pull it off).
THEN he called NK to tell her he already killed Nicole and to come help him with the rest of the plan and help him dispose of the body.
They had possibly planned to cover up their online tracks before they actually set out to murder Nicole, but didn't have time for it now and started acting on spur of the moment decisions, which made them act sloppy, both online and IRL.
It kinda would explain why NK wasn't present, but was willing to help afterwards, and also why she was spilling the beans right away and in the way she did. She was probably pretty miffed she missed 'it', but at the same time didn't see how she was still a suspect, since
they never carried out the
plan. She just helped with a little 'cleanup'.
In NK's mind, DE going it alone totally exonerated her, so she couldn't care less about being arrested (hence the cheery attitude in the booking video). The pics of her later looking less-than-happy were probably taken after reality set in that she was indeed still 'on the hook'.
Idk. This theory still rattles at points but I could see something like this having gone down. The key point being DE killed Nicole sooner than him and NK had planned.