It's too late for me to read that, but I'll share my views on cop killing and you can fit it to whatever incident you want.
If the person was clearly in need of a thrashing, and said thrashing wasn't in excess of the amount needed to subdue the perp, then bravo to the cops. Sometimes, people die when they get in scuffles with the police. No need to villify a cop for doing his job.
However, to kill someone with a baton, you basically have to hit them in the neck or head with it. That's not safe, and the cop should have known better.. Cops generally aim for center of mass, or legs or arms - a good hit with a baton will put that limb out of commission. but if the kid was fucking around with a cop, he should have known better.
Tragic, yes, criminal, maybe not.
EDIT: Reading other responses, this was probably one of those unprovoked attacks we've seen lately.
If that's the case, the cop should burn.