From the video transcript posted upthread:
50:53 LINDSAY FAIRLEY When Karlie was picked up by stepmom, Karlie was scared to get in her car and said she was scared she was going to kill her.One point Karlie reached to the front seat and grabbed the steering wheel.
Why was Karlie in the back seat?
There is
no data to support overdose/death related to any of these drugs put out as possibilities so far:
Marijuana (THC)
Marijuana Overdose: Is It Even Possible to Die from Cannabis?
Why overdose may be the wrong word when it comes to cannabis | CBC News
Of note is the potency and effects of marijuana edibles, as you can take in a very high dose of thc versus smoking over a short period of time. This can easily make you sick or feel like you're going to die while not being caused by real physical toxicity(I've had this experience).
LSD
The way LSD interacts with the body makes it extremely unlikely to die as a direct result and there is no known overdose or toxicity level (you might jump off a cliff while hallucinating, but it is the fall that kills you)
https://www.drugpolicy.org/sites/default/files/LSD_Facts_Sheet.pdf
https://maps.org/research-archive/w3pb/2008/2008_Passie_23067_1.pdf
Other potential psychedelics like shrooms, MDMA or its derivatives also have no overdose evidence.
I personally conclude from this that she did not die of an overdose if she indeed was under the influence of one of these, or if she did, that she was on meth, K2 or bath salts. I can't see her doing these when marijuana is readily available. If she s dead, it is because she was killed IMO.