The lead investigator wanted to charge Zimmerman with manslaughter in the weeks after the shooting but was overruled.
These are among the details revealed in nearly 200 pages of documents, photos and audio recordings that were released Thursday. Yet it's still unclear what exactly happened and whether it was racially motivated.
The evidence supporting Zimmerman's defense includes a photo showing the neighborhood watch volunteer with a bloody nose on the night of the shooting. A paramedic report says Zimmerman had a 1-inch laceration on his head and forehead abrasion.
"Bleeding tenderness to his nose, and a small laceration to the back of his head. All injuries have minor bleeding," paramedic Michael Brandy wrote about Zimmerman's injuries in the report.
Whether Zimmerman, 28, was injured in the Feb. 26 altercation with Martin has been a key question. He has claimed self-defense and said he only fired because the unarmed teenager attacked him.
Zimmerman was not arrested for weeks because he invoked Florida's "stand your ground" law, which does not require a person to retreat in the face of a serious threat. He was released on bail and is in hiding while he awaits trial on a second-degree murder charge. He has pleaded not guilty.
Other evidence supports the contention of Martin's parents that Zimmerman was the aggressor.
The investigator who called for Zimmerman's arrest, Christopher Serino, told prosecutors that the fight could have been avoided if Zimmerman had remained in his vehicle and awaited the arrival of law enforcement. He said Zimmerman, after leaving his vehicle, could have identified himself to Martin as a concerned citizen and talked to him instead of confronting him. The report was written on March 13, nearly a month before Zimmerman's eventual arrest.
He said there is no evidence Martin, 17, was involved in any criminal activity as he walked from a convenience store to the home of his father's fiancee in the same gated community where Zimmerman lived.
The lawyer for Martin's parents seized on the investigator's recommendation.
"The police concluded that none of this would have happened if George Zimmerman hadn't gotten out of his car," attorney Ben Crump said. "If George Zimmerman hadn't gotten out of his car, they say it was completely avoidable. That is the headline."
The case has become a national racial flash point because the Martin family and supporters contend Zimmerman singled Martin out because he was black. Zimmerman has a Peruvian mother and a white father.
The autopsy says medical examiners found THC, the psychoactive ingredient in marijuana, when they tested Martin's blood and urine. A police report shows he had been shot once in the chest and had been pronounced dead at the scene. The autopsy says the fatal shot was fired from no more than 18 inches away.