Alice Walker's reflections on the killing of Trayvon Martin.

The chain of events that directly led to his killing started when a white racist assumed a young black man was a criminal mainly because of his looks, then pursued him. That must happen fairly often in the US. If it leads to a fight, there is some chance one of the people will be killed (most likely the young black man).

A crucial psychological principle is that the probability of punishment and the frequency of punishment matter more than the amount of punishment. If we want to prevent repetition of this chain of events, it would be more effective to punish or discourage some event near the start, rather than an unusual outcome. Perhaps limiting carrying concealed weapons is a good solution.