"There are no monsters here," Don West, a defence lawyer, said in his opening statement, denying the contention that his client had chased and then confronted Trayvon, who was black, in part because of his race.
"George Zimmerman is not guilty of murder. He shot Trayvon Martin in self-defence after being viciously attacked." He added: "He shot Trayvon Martin because he had to, in self-defence."
But the prosecution promised that it would prove that Zimmerman was never attacked by the teenager. From the start, Guy said, the defendant had spun "a tangled web of lies" about the shooting to protect himself.
"George Zimmerman did not shoot Trayvon Martin because he had to. He shot him for the worst of all reasons - because he wanted to."
Just before the trial's opening Judge Debra Nelson barred the prosecution from introducing testimony from voice experts who were to argue that screaming heard on another emergency call tape was that of Trayvon. But Guy said jurors would hear the call and be able to make up their own minds.
"In the background, you will hear the gunshot that killed Trayvon Martin and you will hear screaming in the background. Listen carefully, please, to that call and listen carefully when the screaming stops. It's right when the gunshot goes off.
"Trayvon Martin was silenced immediately when the bullet the defendant fired was shot through his heart," Guy said.
The trial will be closely watched in part because of the national debate that was stirred by the killing and the decision by Sanford police initially to release Zimmerman on the basis of Florida's controversial self-defence laws known as "stand your ground".
After outrage spread, especially in America's black community, a special prosecutor was appointed to look into the case and Zimmerman finally turned himself in. The Sanford police chief was subsequently fired.
What they said
• Prosecution: John Guy
"When he saw Trayvon Martin, he didn't see a young man walking home. He saw someone that looked 'real suspicious' - somebody that looked like they were 'up to no good' ...
"(Zimmerman) believed it was his right to rid his neighbourhood of anyone he believed did not belong."
• Defence: Don West
"A young man lost his life, and another is fighting for his. There are no monsters here ...
"He had just taken tremendous blows to his face, tremendous blows to his head. Trayvon Martin armed himself with a concrete sidewalk and used it to smash George Zimmerman's head."
- Independent
