Also while I'm thinking about it, while it didn't lead to riots directly, the case of Raoul Moat in this country in 2010 shows that there is a mistrust of the police in some communities that can be easily provoked. There was all that "Raoul Moat you hero [for shooting a police officer who had nothing to do with anything in Moat's life...]" reaction, for one thing. In the end Moat shot himself first, but if he had indeed been shot by the police it's possible that people could have used his death as a rallying cry for protests. Or, more likely, just an excuse to go and do some looting. pillaging etc.
Which perhaps is the broader point, that there are two different reactions in both this story and that of the August 2011 Riots. Initially there was a protest at the death of a young (black) man that had been shot in circumstances that at least on the surface looked like it was racial profiling. That protest was legitimate and even now there is a case to be made that he shouldn't have been shot, as "the official story has undergone numerous changes" [Wikipedia... I would like a more official source for that but I believe it's been widely reported in the news]. But then this protest just got hijacked and soon there were riots all over the country that had nothing to do with the initial death but were pure and simple opportunism. To an extent, the same thing is true here -- and the opportunists were then, and are now, of all kinds of different racial background.