people are not angry that a white person killed a black person or that mr. zimmerman may have been racist. it is simply, at least in my mind, that initially the police did not investigate this crime properly. the assumption was that because trayvon was young and black that he was up to no good and despite trayvon not having a weapon, was still viewed as so dangerous the police did not arrest mr. zimmerman for killing him-they didn't detain him at all. the assumption, for whatever reason, was that mr. zimmerman was innocent of any crime and trayvon must've been guilty of some crime.
i haven't been keeping up with the story, but that is how i see things.