I found myself in a brief debate with a cultist regarding the autopsies of George Floyd. (One was the official autopsy performed by the Hennepin County Medical Examiner, and the other was an independent autopsy performed by the former M.E. for New York City). Both Medical Examiners arrived at the same conclusion (homicide), though their opinions differ on whether the root cause of death was mechanical asphyxiation or the heart-attack caused by the asphyxiation.
I'll save you the story of the whole dreary encounter wherein the "evidence" my cultist interlocutor cited was a sensationalized video claiming that George died of a drug overdose.
Fast forward to me spending two hours studying the post-mortem, vs. ante-mortem pharmacokinetics of fentanyl. On the off chance that any reader here is interested, there is a good and quite readable paper in the journal "Clinical Toxicology". I link that paper below.
Here's the tl;dr of the paper:
"Postmortem blood fentanyl concentrations do not correlate directly with antemortem blood concentrations. Without adequate evaluation of kinetic data, investigative information and consideration of postmortem changes, misinterpretation of postmortem fentanyl results is likely"
Before someone asks: pharmacokinetics is the study of the distribution, absorption, and metabolism of a drug over time.