Yes, and if you read much outside of here, I am one of many thousands who thinks it is very possible. Things like this have happened before.
I grew up with cops, and many were fine, but.......some people are hot headed, and can't handle the job. I have a cousin that had the worst temprement for it- loved to intimidate people for kicks, bad temper. Got in a lot of "scapes" but never was written up once.
The adrenaline that shoots through you after firing a weapon can make you absolutely manic. My brother was a union delegate for almost 30 years and saw both sides of this, many cops were accused of things they did not do, but quite a few abused their power too. Too many drank and appeared to abuse cocaine or steroids. It would take quite a bit of questionable behavior before any cop lost the benefit of the doubt from their fellow officers. It's just how they do, protecting their own.