Assuming this claim is true the cop still appears to have been seriously negligent.But,again assuming it’s true,it could lower the criminal (and moral) culpability to some degree of “negligence” (”Negligent Homicide”,for example) rather than flat out “murder”.
The issue will be depraved indifference, which supports a murder charge. I doubt he’ll claim negligence, the warnings by bystanders and I believe one leo, coupled with his lack of movement and fluid discharge would argue against that.