The Department of those officers is not investigating them, but instead transferred the investigation to another department. They will face disciplinary action and if found to have used excessive force, they will be punished to the letter of the law.
This works in principal, not in reality. There are plenty of cases where the 'I'll scratch your back, you scratch mine' is full in effect in police circles.
Ian Bush was shot in the back of the head in a holding cell after being arrested for being drunk in public and giving the police officer a fake name (he said his name was one of his buddies that he was with, much like what kids do for substitute teachers). The police officer said it was in self defence and he was found innocent by another department. That other department, by the way, was being investigated at the same time by that office for a similar offence. Both departments found the other departmental parties innocent.
In fact, police officers are now no longer able to be recorded doing their job (i.e. you're not allowed to film an arrest) in many states, often because when its recorded, you realize just how many officers are bending the rules and using force, or out right assaulting people and then lying about it.http://gothamist.com/2008/07/28/cop_caught_on_video_assaulting_cycl.php
for instance is a scenario where a cop maliciously singles out and attacks a man, and then charges HIM with assault, resisting arrest, and disorderly conduct. It was only after the video was released that the officer resigned, though he was cleared of the assault charge after the fact.
Cops are not being held accountable. The investigations they do are often shoddy, and lack transparency and input from outside agencies.
I know a wonderful man, an excellent officer, and he is just disgusted by the corruption of the system by people who are little more than bullies who want to push people around. I realize you'll hear about the bad cases more often than the good, in all things, but still. There are too many cases where police have used excessive force and gotten away with it because there was a lack of video evidence because they turned off the cameras before beating someone in a holding cell.http://www.seattlepi.com/default/article/Beating-caught-on-police-video-1301303.php
was a recorded beating of a 15 year old girl in a holding cell, for instance. Without that video, it's not likely that anyone would have trusted a 15 year old accused criminal over the word of a police officer.http://toronto.ctv.ca/servlet/an/local/CTVNews/20100928/bc_kinloch_power_abuse_100928?hub=OttawaHome
was a recorded tethering of a 15 year old girl in a cell in Toronto. Again, if this wasn't taped, it's not likely there'd be any repercussions for the officers. Who would believe a 15 year old that was drunk at the time over the word of an officer?
So while I believe that cops that are videotaped or photographed doing something criminal often to suffer repercussions, it seems that if there's no video evidence, they don't face charges. And they're working to make video taping or photographing police officers doing their job a crime. That's frightening, to me.