While I'm sympathetic to your comment in isolation, do you think there is any chance that after the slow wheels of justice do turn, these violent thugs and their facilitators are actually going to end up in prison for armed assault, robbery, kidnapping, criminal conspiracy, etc? This is the breakdown in the rule of law that people are outraged about, regardless of the somewhat unreasonable desire that justice should happen quicker. If justice were merely slow but still dependable, people wouldn't be nearly as outraged.
Also if there were a consistent pattern of rogue law enforcement employees getting designated as having acted outside of their state-granted authority, prosecuted as regular criminals, and going to prison, this particular incident would have been less likely to happen in the first place. So given the larger context it's a bit specious to say we just need to give the situation time, when time mostly serves to make the widespread attention fade.