The medical examiner in Minneapolis says that Floyd did not die from asphyxiation or strangulation. They are waiting for toxicology reports. Read the arrest report here.(pdf alert) This is going to make it very difficult to get a conviction.
Note that the ME report says that the cops holding him face down “likely” contributed to Floyd’s death. The standard is “beyond a reasonable doubt.” Likely won’t be good enough, it has to be a sure thing for a criminal case.
If he didn’t directly die from the officer’s actions for certain, they have an uphill battle here.