According to one such narrative, the case is about race, which was the reason Zimmerman, a 29-year-old neighborhood watch volunteer, thought Martin, a black teenager, looked "real suspicious" and the reason Zimmerman was not initially arrested for shooting Martin. According to another, complementary narrative, the case is about Florida's broad definition of self-defense, which gave Zimmerman license to kill Martin. But it turns out neither of these factors is relevant to Zimmerman's guilt.
Zimmerman called the police about Martin before he got a good enough look to verify the 17-year-old's race, and there is little indication that he harbored animosity toward blacks. The most explicit reference to race during the trial was a prosecution witness's testimony that Martin, who was on the phone with her shortly before he died, referred to Zimmerman (who is Hispanic) as a "creepy-ass cracker."
Maybe a black man who killed a white teenager in similar circumstances would have been arrested sooner. But that counterfactual has no bearing on whether Zimmerman should be convicted.
The outrage triggered by the six-week delay in arresting Zimmerman probably encouraged special prosecutor Angela Corey to accuse him of second-degree murder rather than the more appropriate charge of manslaughter. That mistake has been apparent every day of the trial, as the prosecution struggles to show that Zimmerman acted out of "ill will, hatred, spite or an evil intent," as opposed to panic in the midst of a fight he was losing.
Zimmerman's account of that fight does not invoke the right to "stand your ground" or any other special feature of Florida's self-defense law. He claims Martin, who was understandably angry about being followed, threw the first punch and was on top of him, knocking his head against a concrete sidewalk, when Zimmerman's holstered gun became visible. Zimmerman says Martin seemed to be reaching for the gun, so he grabbed it first, fearing for his life, and shot Martin in the chest.
The evidence supporting this version of events, though by no means conclusive, is ample cause for reasonable doubt about Zimmerman's guilt. His injuries -- including a bloody, possibly broken nose, plus bumps and lacerations on the back of his head -- are consistent with his description of the fight.