The media has already decided that George Zimmerman is guilty of murder, despite the fact that after several weeks he hasn't even been charged with a crime. There is absolutely zero reason to believe that George Zimmerman is guilty of murder. A review of the facts will show that the only charge he might be guilty of is manslaughter.
Since most of us are familiar with the background of the case I'll dive right into it-
(1) George Zimmerman called the police on the non-emergency number to report a suspicious person in his neighborhood (Presumably Trayvon Martin). During the phone call he reported that this person had spotted him and was running away. The police asked him if he was following him and he said he was. The police then advised him that this was unnecessary, he (apparently) aquiesced by saying, "okay."
(2) After that he stayed on the line with police and discussed where they could meet him. Eventually he told them to call him when they got there and he would meet them. From this point we don't have much evidence of what happened next.
(3) A short time later neighbors hear a scuffle outside. A man named "John" looks out and see's Trayvon Martin on top of George Zimmerman punching him in the face. George Zimmerman screams for help and for someone to call the police, (according to John). John, (who is also the sole eyewitness as far as I know), runs to call the police but hears a shot before he can get there and sees Trayvon Martin dead and George Zimmerman standing over him.
(4) When police arrive they find George Zimmerman bleeding from the nose and back of his head, he also has grass stains on his back. Trayvon Martin is dead from a gun shot wound to the chest. Police interview witnesses and take George Zimmerman into custody. They also interview George Zimmerman at the police station without an attorney.
(5) All we know is that a fight occured between two men, and one ended up shot in the chest. George Zimmerman claims that he was attacked as he walked back to his truck, there are no eyewitnesses to how the altercation started. If George Zimmerman started a fight then pulled out a gun once Martin got the upper hand he is guilty of Manslaughter, if Trayvon Martin attacked George first then it is self defense. Either way it is almost impossible for George Zimmerman to be guilty of murder.