I agree that it will be difficult to charge with first degree on the evidence that we know about. Due to lack of evidence, second degree may be the highest charge he gets. That still puts him in the lane of possibility for as much as life without parole and as little as ten years.
I don't think he's just crazy, though, and I'm not sure it was just drugs or heat of the moment. It's hard to know. It may very well have been. Sociopaths tend to process drugs and alcohol differently than the vast majority of people and it's possible his anger was fueled more by lack of control and his perception of how he was being treated at that party.
A witness also stated to a private detective that he admitted to her what he did to Kara and he loved doing it.
https://crimewatchdaily.com/2016/06/02/family-searches-for-answers-in-missouri-teens-disappearance/
That doesn't speak to heat of the moment killing to me. That speaks volumes about the kind of person he is. I also don't think we would have gotten the snarky, smirking man walking out of the jail in Edwards to be transported to KC if this were just a heat of the moment killing involving drugs. I know I've said it many times here, but it will take a lot to convince me that he's not a sociopath with something like antisocial personality disorder fueling him to do what he's done. The circumstances surrounding his childhood, the animal abuse, drug and alcohol addictions, aggression, lying, intense control issues, repeat offenses, impulsive and reckless behavior...all signal that he is a sociopath. If he's just crazy, so be it. He can take the psychological testing through the court and plead insanity. But I think there's a lot more going on than that.