George Zimmerman was merely a good citizen looking out for his neighborhood when he was confronted and attacked by Trayvon Martin in February 2012.
So his defense attorneys claimed in opening statements Monday, in a stark contrast to prosecutors' picture of a vigilante who profiled the Florida teen.
Zimmerman, 29, a former neighborhood watch volunteer, is on trial for second-degree murder; he claims he shot the teen in self-defense in Sanford, Fla.
"George Zimmerman is not guilty of murder," his attorney, Don West, said.
"He shot Trayvon Martin in self-defense after being viciously attacked. The evidence will show you how and why it happened the way he did."
West described the case as "sad," and said, "there are no monsters here."
"[Martin's mother] Sybrina Fulton and [Martin's father] Tracy Martin are grieving parents. Without question, they have a right to grieve," West said.
"They have a right to feel how they feel."
Using diagrams, however, West set out to convince jurors in detail of the defense's version of the events, which he believes will clear Zimmerman.
After calling a non-emergency dispatcher to report a suspicious person, West said, Zimmerman got out of his car to give the dispatcher more information.
When the dispatcher told him not to follow Martin, West said, he stopped.
In a contrast to the state's version of events, West said that Trayvon Martin was the first to confront George Zimmerman after the phone call ended.
"Trayvon Martin decided to confront George Zimmerman instead of going home. He had plenty of time, but he chose not to do that," West said. "He turned to George Zimmerman."
"Out of the darkness, he said, 'Why are you following me?'"
Trayvon Martin was the aggressor on the confrontation that ensued, West said.
He said a witness would testify who saw Zimmerman and Martin struggling - a neighbor who said he saw Martin on top of Zimmerman in the moments before the fatal gunshot.
"[The neighbor] called it a 'ground and pound.' That's the words he used," West said.
"A ground and pound is when you're mounted on someone, they are helpless, and you are basically beating them senseless."
West also showed the jury pictures of Zimmerman bleeding from the face after the altercation and played a recording of a neighbor's call to 911.
During that 911 call, screams for help can be heard in the background.
The disputed 911 tape was the subject of much pre-trial wrangling, with defense experts arguing the quality was too poor to reliably analyze who was screaming on the tape.
"What we know, everyone will agree to this... those are the screams of someone in a life threatening situation," West said.
"Someone screaming repeatedly, over and over and over again for help, needing desperately for someone to come to their assistance."
In their opening statements earlier, prosecutor John Guy implied that it may have been Trayvon Martin screaming in the background of the call.
"Listen carefully please, to that call. Listen carefully ... when the gunshot goes off, Trayvon Martin was silenced immediately," Guy said.
"When the bullet the defendant fired passed through his heart, when that gunshot rings out on the 911 call, the screaming stops."
Guy portrayed Zimmerman as a vigilante who profiled Martin as someone who was about to commit a crime in his neighborhood, followed him, confronted him, and murdered him.
"'[Expletive] punks,'" Guy said, recounting Zimmerman's words in the call to non-emergency dispatchers.
"'These [expletive,] they always get away.' Those were the words in that grown man's mouth as he followed in that dark a 17-year-old boy who he didn't know."
"Those were the words in that man's chest when he got out of his car armed with a fully loaded semi automatic pistol and two flashlights to follow Trayvon Martin."
Martin, Guy said, "was walking home from a 7-Eleven armed with 23 ounces of Arizona brand fruit juice and a small bag of Skittle candies."
In sharp contrast to Guy's opening statement in which he dramatically quoted Zimmerman's obscenity-laced remarks, West included a "knock-knock" joke in his remarks.
"Knock, knock, who's there? George Zimmerman. George Zimmerman who? All right good, you're on the jury. Nothing? (audience laughs) That's funny," said West.