Assault and murder indictments and charges are far less common, though not impossible to attain.
If the average citizen assaulted someone like this cop did, he would be in jail in a minute with all kinds of charges against him. He would be facing prison.
The reason cops get out of it is simply ONE. When people file charges against a cop individually and personally, they file against the officer rather than the man. If they filed against the man, man to man, who used the office of government to commit the crime, things could be different.
Almost nobody files against the man. They always file against the city, the police department, or the officer. The officer is not the man. The man has no immunity.