Sorry, I must not have been too clear with that part: I didn't suppose that DE joked and NK took it literally. I said maybe DE joked and they both for a bit took up a kind of dark joking about murder as the answer (nonmurderous folks do that, sometimes), both knowingly joking -- but then got to a different plan, a real plan, about confronting, talking to, scaring, whatever, but not murder.
My reason for even proposing that hypothesis was as explanation for why there would be "soundbites" (quotes scattered here and there in print, actually) of NK referring to comments about slitting throats, etc. I was thinking that, when LE was interrogating NK, she might have revisited that DE conferred with her about the "Nicole problem". Since Nicole is now dead, NK may have been asked if their discussion ever involved scenarios of violence/murder. She might have (honestly) answered, well, yes...but only as joking. But with Nicole dead, LE likely would not have taken that at face value.
One really weird twist is that, if DE and NK DID joke about murder but then move on to a real-life plan not involving violence...and if NK really did not see Nicole receive the fatal wound (and most media reports seem to say NK has said she did not witness that) -- then I'd think NK would at some point have to have her own doubts about whether Nicole stabbed herself...say, if that's what David told NK happened.
As for being tried separately. Wow, I really don't know. But I will say: Just my own current hunch is that one or both cases may not got to trial. I think we may see some pleas.
