The cause of death, which everyone has been consistent on, was cardiac arrest. The second autopsy, which you claim I conveniently left out, was as bias as it gets. It was done by the plaintiff counsel's go-to medical examiner of record whenever you need a race motivated crime, Michael Baden. This is the same guy who argued about every police shooting he ever saw, including Michael Brown where he was massively discredited in the legal process as being reckless and intentionally misleading.
In the legal world there are obvious defense and plaintiff experts, people who will consistently opine on the same side of the case no matter the circumstances, arguably the best example is Baden and people don't take him really seriously as a result. Meanwhile, actual public office holders citing actual medical evidence and indications are a much more reliable source of information.
The ultimate problem with this entire argument (ie: he was strangled/asphyxiated) is that he was complaining about having breathing troubles before he was on the ground at all. He in fact started complaining relatively early on while still standing outside the patrol car. What does that tell you? It tells you that he wasn't being physically acted on but that the stress of the situation, combined with his already extremely poor health along with his acute intoxication of illegal drugs were causing a cardiac event. The guy was a walking dead man at that point. Look at the statistics I noted above for arterial diameters and constrictions. Do you have any idea how much trouble you are in when you have 90% occlusions of major cardiac arteries? You realize that doesn't mean you have a 10% flow capacity, but instead more like a 1-2% capacity?
Imagine getting into any sort of physical struggle, or even mentally stressing event and you were breathing through a coffee stirrer. Then add the drugs.