Here's a piece by Reuters of all things---where they did something unprecedented in the entire case---they investigated instead of making shit up.
Amongst the nuggets---Zimmerman, the white racist, is part black. He didn't join the neighborhood watch on his own initiative, he was asked to. He didn't get the gun on his own, he was advised to by an animal control officer. The neighborhood had been terrorized by young black men, which point one of Zimmerman's black neighbors makes. There's more, and the article, by a noted liberal news outlet is worth reading in it's entirety to get the context under which this happened.
It paints a very different picture than the media has given so far, at the very least. None of which proves Zimmerman didn't act out of character, or snap or whatever, but given the other evidence, including the eyewitness report and physical evidence, seems to make it impossible to prove second degree murder, or even manslaughter.