What about the toxicology report from the coroner's office that conducted his autopsy?
The county he was in performed an autopsy that said he died of a heart attack. Then the family didn't like that, and ordered their own independent autopsy, which came to the conclusion that he died of mechanical asphyxiation. Thing is, Floyd had a history of heart troubles, said he couldn't breathe before being restrained on the ground, and had a lethal dose of fentanyl, as well as methamphetamine in his blood stream.
Edit: important bits at the bottom of this post:
https://www.cbsnews.com/news/george-floyd-death-autopsies-homicide-axphyxiation-details/#app
But the report released later Monday by the Hennepin County Medical Examiner's office said Floyd died of "cardiopulmonary arrest complicating law enforcement subdual, restraint and neck compression." The manner of death was ruled homicide, but the office noted that "is not a legal determination of culpability or intent." A preliminary autopsy report cited earlier by prosecutors said the county medical examiner's review "revealed no physical findings that support a diagnosis of traumatic asphyxia or strangulation."
Below is the link to a sketchy news site, which I am only linking because halfway down it shows the PDF from the coroner's office of all the drugs they found in his system when they did a tox screen:
You'll notice it says he had 11 ng/ml of fentanyl in his bloodstream, 5.6 ng/ml of norfentanyl (another synthetic opiate analogue), and 19 ng/ml of methamphetamine. Again, only linking Fox because they link to a PDF from the Hennepin County attorneys office, which I would encourage people to download and read, its only 2 pages. But notable quotes are below:
https://www.foxnews.com/us/medical-examiner-george-floyd-fentanyl-system
Fentanyl — 11. He said, “that’s pretty high.” This level of fentanyl can cause pulmonary edema. Mr. Floyd’s lungs were 2-3x their normal weight at autopsy. That is a fatal level of fentanyl under normal circumstances.
AB said that if Mr. Floyd had been found dead in his home (or anywhere else) and there were no other contributing factors he would conclude that it was an overdose death.
To me, this seems to complicate things and pushes against the narrative that it was purely mechanical asphyxiation from Chauvins knee that killed Floyd.