@snood,
I've seen cases where a cop has killed someone who clearly should not have been fired upon, so
yes.
The cops were mistaken and acting in good faith though, not acting out of malice.
You know, some 90 years ago the county sheriff shot up my great uncle while he was unarmed. He didn't sit around whining about it. He ran inside and grabbed his shotgun, and put a 12 gauge slug in the back of the sheriff's head.
I recently got to hold "the shotgun". It's a legendary heirloom in my family and some relatives are going to have it restored and mounted, so it came out of storage for the first time in a number of decades.