I don’t think it was racially motivated. I think Zimmerman just didn’t practice good sense and proper security measures.
Alas, Martin was not up to snuff on his situational awareness and self-defense skills. Perhaps, if he had been, he'd be still alive, and the village would be short an idiot, shot by his own gun!
Col. West for VP!
It is easy to say that Zimmerman didn't practice good sense in hindsight, but unless you have some other information the police don't, then it is understandable why the police could not arrest him.