Here is the difference. The police accidentally grenaded the kid (they obviously didn't mean to do that to a baby). Frein purposely killed the police offer (while in a hiding surprise attack).
The police who "accidentally" grenaded Baby Bou Bou did so in the course of attempting to kidnap a man who (so far as I have heard) had done NO harm to any person or property.
But crimes committed by police as part of "just doing their jobs" are officially sanctioned by the state.
Crimes committed against police are not.
The murderers of Kelly Thomas, Aiyana Jones, Eric Garner, Jose Guerena, etc., etc.,
ad nauseum have badges.
They will NOT be punished (with exceedingly rare exceptions).
Eric Frein does not have a badge.
Eric Frein WILL be punished.
THAT is the only difference here.
I can't help but wonder: if I tried to capture a man who had done nothing wrong and was no threat to me just in order to "fine" him (i.e., extort money from him) and/or lock him up in a cage, and I "accidentally" grenaded a baby in the process of doing so, would you be here explaining how it was "just an accident" and that I "obviously didn't mean to do that to a baby?" Or would you just denounce me as a vicious baby-mangling criminal? If you have a shred of decency, you would do the latter -
so why should it make any difference if I happened to have a government-issued badge?
Now, you can fault the police for being a part of the raid that, their line of work, or other, but there is a difference. The real blame is the laws/code that says the officers need to do these raids to get drug offenders. The officers are just doing their job, so lets change their jobs so they wont be doing that anymore.
Ah, the old "just doing their jobs" dodge.
Well, Nazi concentration camp guards were "just doing their jobs," too. [h/t
Godwin's Law]
(So I suppose your advice to Jews, gypsies, etc. would have been for them to "change their overseers' jobs" ...

)
Why should it be incumbent upon the victims to "change the jobs" of their victimizers - instead of incumbent upon the victimizers to change their jobs (or just stop doing those jobs)? (And if most of them are the "good apples" they are allegedly supposed to be, why do they need someone else to "change their jobs" for them?)