It was the first day in a trial that has attracted international attention and prompted nationwide debates about gun control, race and equal justice under the law.
Prosecutor John Guy's first words to jurors were "F------ punks, " as he recounted what Zimmerman told a police dispatcher in a 911 call before the confrontation with the Miami-area teen. Guy immediately had the jury's attention.
Guy told jurors that Zimmerman "murdered" Martin because of his temperament, his MMA training and his anger that "these a------- ... always get away." As he made his arguments, Guy pointed a finger at 29-year-old Zimmerman, glaring at him for a second to two longer than is comfortable.
Zimmerman was profiling Martin as he followed him through the gated community, Guy said.
"He shot him for the worst of all reasons: because he wanted to," he said.
Zimmerman has pleaded not guilty to second-degree murder charges for Martin's death on Feb. 26, 2012. Defense attorney Don West told jurors that Zimmerman was being viciously attacked when he shot Martin. Zimmerman was sucker-punched by Martin, who then pounded Zimmerman's head into the concrete sidewalk, West said.
When jurors heard two police dispatch phone calls, they began to take notes. The first was a call Zimmerman made to a nonemergency police dispatcher, who told him he didn't need to be following Martin. West walked the jury methodically through the call, pointing out that Zimmerman did not follow Martin after he was told not to.
The second 911 call captures screams from the confrontation between Zimmerman and Martin. Martin's parents said the screams are from their son while Zimmerman's father contends they belong to his son.
"I think the evidence will show that this is a sad case," West said. "There are no monsters here."
West said Zimmerman spotted Martin walking into the gated community and did not recognize him. There had been a rash of recent break-ins, and Zimmerman was wary of strangers walking through the complex, West said.
ABC News and The Associated Press contributed to this report.