I'm remembering echoes of other cases, where a woman demanded her boyfriend murder a rival.
Were NK and DE in a relationship?
It seems clear now that this wasn't a case of Nichole unexpectedly becoming sick and dying while with David.
I don't think you can eliminate an accidental killing in the course of a statutory rape. NK was not charged with murder, there is no evidence and the police have no evidence she was involved in the commission of a murder.
It could very well be the case that he lured Natalie out of her room for sex, and either something went wrong, like she was drinking and got sick, or he went into a rage and killed her, or he even set out to kill her. She was only charged with felony disposal of a body and a misdemeanor crime. Natalie could have died and he could have called his friend NK in after the fact. I wonder if maybe the perp did not have a car but NK did and that is how she got herself involved? He needed her car to move the body and that is how she is involved. If her involvement is like that I am sure she would be singing as a canary now telling the police what she knows. Given they found the body and are searching the lake I suspect she is.
The Diana Samaro angle (TX cadet case) seems not be to be scenario here given that she was not charged with murder. Moreover, police are getting info from somewhere, I suspect it is her. While it is one scenario that this was a nefarious couple murder, the evidence presented so far and the inferences we can take from them suggest the above scenario I pose is a possible scenario.
The Samaro case took months to solve because both held firm for many months. That is usually the case with these couple murders.