George Zimmerman was obviously responsible, of course. Nothing hidden there at all, except from the willfully blind police. Zimmerman didn’t just murder Trayvon in cold blood, he had tracked him down like dog. The 911 tapes released so far include Zimmerman talking of “suspicious” black men: “These a**holes always get away.”
Because the police dispatcher expressly told Zimmerman not to follow Martin, because Neighbourhood Watch guidelines forbid the carrying of guns, as well as the pursuit of suspects - requiring Watchers to call the police to the scene - not to mention the fact that Zimmerman wasn’t actually part of a registered Neighborhood Watch group, and was a failed, wannabe cop who’d actually been arrested for attacking a real police officer - because of all that, it is perfectly obvious that Zimmerman’s “Neighborhood Watch” activities were nothing but a ruse and a fantasy. Murdering a black teenager had arguably been Zimmerman’s underlying (if perhaps unconscious) motive for everything he’d done for at least the past year, if not for wanting to be a cop in the first place.
Paul Rosenberg, "Who Killed Trayvon Martin"; Al Jazeera 2012.