I know what I'm about to type sounds callous, I too think this was a failure of policing. I just don't know that I agree with the convictions.
Until he lost consciousness, Floyd never stopped resisting. Floyd weighed what...210? Chauvin is 160. Placing the knee on the neck is (or was) an approved suppression tactic--until this incident police used it ALL the time. If Chauvin's total weight was on Floyd's neck, why no bruising or contusion? The cause of the asphyxiation is what was at issue. An overdose of drugs could precipitate the kind of asphyxiation that killed him. Plus, as I mentioned above, why did the Prosecution not want testimony from the fellow who was in the car with Floyd when he was arrested? If it's the truth we're after, these questions are fair game for discussion.