The autopsy indicated that both of these were instrumental in causing Garner's cardiac arrest.
I also know that grand juries almost never decline to indict. It's not a system where evidence is challenged; it's almost always a mere formality. It certainly doesn't match the level of scrutiny of a full file.
But hey, why talk about police brutality and injustices of the courts, when we can bitch about taxes?
It’s Incredibly Rare For A Grand Jury To Do What Ferguson’s Just Did | FiveThirtyEight