I am guessing that this was revenge for something she said or did while being processed, which cops can't do, either. If she resisted being put in the cell, let the video record that and show it at trial.
Working in a jail you are going to get yelled at, spit at, bit, puked on, an occasionally somebody goes full primate and starts flinging poo. If you can't handle that you should get another job. If you are working the jail waiting for a street cop job to open up and can't stand the jail you shouldn't be on the street. There you need to cuff, and treat like a human being, the guy that just tried to kill you,
If she reacted to something, that caused the cop to do that to her, I’m going to guess that it wasn’t a mug shot she had a problem with, but the strip search.