During closing arguments, Zimmerman's lawyers put a concrete slab and two life-size cardboard cutouts in front of the jury box in one last attempt to convince the panel Zimmerman shot the unarmed black 17-year-old in self-defense while his head was being slammed against the pavement.
Attorney Mark O'Mara used the slab to make the point that it could serve as a weapon. He showed the cutouts of Zimmerman and Martin to demonstrate that the teenager was considerably taller. And he displayed a computer-animated depiction of the fight based on Zimmerman's account.
He said prosecutors hadn't met their burden of proving Zimmerman's guilt beyond a reasonable doubt. Instead, he said, the case was built on "could've beens" and "maybes."
"If it hasn't been proven, it's just not there," O'Mara said. "You can't fill in the gaps. You can't connect the dots. You're not allowed to."
In a rebuttal, prosecutor John Guy accused Zimmerman of telling "so many lies." He said Martin's last emotion was fear as Zimmerman followed him through the gated townhouse community on the rainy night of Feb. 26, 2012.
"Isn't that every child's worst nightmare, to be followed on the way home in the dark by a stranger?" Guy said. "Isn't that every child's worst fear?"
One juror, a young woman, appeared to wipe away a tear as Guy said nothing would ever bring back Martin.
The sequestered jury of six women all but one of them white will have to sort through a lot of conflicting testimony from police, neighbors, friends and family members.
Jurors deliberated for three and a half hours when they decided to stop Friday evening. About two hours into their discussions, they asked for a list of the evidence. They will resume deliberations Saturday morning.
Witnesses gave differing accounts of who was on top during the struggle, and Martin's parents and Zimmerman's parents both claimed that the voice heard screaming for help in the background of a 911 call was their son's.
Zimmerman, 29, is charged with second-degree murder, but the jury will also be allowed to consider manslaughter. Under Florida's laws involving gun crimes, manslaughter could end up carrying a penalty as heavy as the one for second-degree murder: life in prison.
The judge's decision to allow the jury to consider manslaughter was a potentially heavy blow to the defense: It could give jurors who aren't convinced the shooting amounted to murder a way to hold Zimmerman responsible for the killing.
To win a manslaughter conviction, prosecutors must show only that Zimmerman killed without lawful justification.
O'Mara dismissed the prosecution's contention that Zimmerman was a "crazy guy" patrolling his townhouse complex and "looking for people to harass" when he saw Martin. O'Mara also disputed prosecutors' claim that Zimmerman snapped when he saw Martin because there had been a rash of break-ins in the neighborhood, mostly by young black men.
The defense attorney said Zimmerman at no point showed ill will, hatred or spite during his confrontation with Martin which is what prosecutors must prove for second-degree murder.
"That presumption isn't based on any fact whatsoever," O'Mara said.
In contrast, prosecutors argued Zimmerman showed ill will when he whispered profanities to a police dispatcher over his cellphone while following Martin through the neighborhood. They said Zimmerman "profiled" the teenager as a criminal.
Guy said Zimmerman violated the cornerstone of neighborhood watch volunteer programs, which is to observe and report, not follow a suspect.
Zimmerman's account of how he grabbed his gun from his holster at his waist as Martin straddled him is physically impossible, Guy said.
"The defendant didn't shoot Trayvon Martin because he had to; he shot him because he wanted to," Guy said. "That's the bottom line."
But to invoke self-defense, Zimmerman only had to believe he was facing great bodily harm, his attorney said. He asked jurors not to let their sympathies for Martin's parents interfere with their decision.
"It is a tragedy, truly," O'Mara said. "But you can't allow sympathy."
With the verdict drawing near, police and city leaders in Sanford and other parts of Florida said they have taken precautions for the possibility of mass protests or even civil unrest if Zimmerman, whose father is white and whose mother is Hispanic, is acquitted.
Zimmerman's brother, Robert, said in a statement he hoped the public would remain calm.
"Though we maintain George committed no crime whatsoever, we acknowledge that the people who called for George's arrest and subsequent trial have now witnessed both events come to pass," he said. "We hope now that as Americans we will all respect the rule of law, which begins with respecting the verdict.
There were big protests in Sanford and other cities across the country last year when authorities waited 44 days before arresting Zimmerman.
About a dozen protesters, most of them from outside central Florida, gathered outside the courthouse as the jury deliberated. Martin supporters outnumbered those for Zimmerman.
The arguments Zimmerman jurors are considering
Jurors deciding whether George Zimmerman committed second-degree murder when he fatally shot Trayvon Martin deliberated for three and half hours Friday before adjourning for the night with a plan to continue Saturday morning.
Before starting their deliberations, they listened to the defense give its closing arguments, followed by a prosecution rebuttal.
The jury of six women heard dueling portraits of the neighborhood watch captain: a cop wannabe who took the law into his own hands or a well-meaning volunteer who shot 17-year-old Trayvon Martin in self-defense because he feared for his life.
Here are key points that prosecutors and defense attorneys made in closing arguments.
Zimmerman's under-the-breath utterance of "F punks. These a-. They always get away" to a police dispatcher while following Martin through his neighborhood is evidence that Zimmerman had hatred and ill will toward Martin. To secure a second-degree murder conviction, prosecutors had to convince the jury that Zimmerman acted with a "depraved" state of mind that is, with ill will, hatred or spite.
Zimmerman ignored a police dispatcher's advice that he didn't need to follow Martin.
The prosecution's star witness, Rachel Jeantel, says she was talking to Martin on her phone when she heard her friend ask a man, presumably Zimmerman, why he was following him. She says she then heard Martin shout, "Get off!" before the phone went dead.
There was none of Zimmerman's blood on Martin's hands even though Zimmerman claims Martin covered his mouth and bloodied nose with his hands.
Inconsistencies in Zimmerman's story show that he's lying. Prosecutors say he lied about why he got out of the car, about not knowing Florida's self-defense law and about how Martin approached him.
Zimmerman's account that Martin was straddling him with his knees around his middle would make it physically impossible for the neighborhood watch volunteer to reach for the gun holstered around his waist.
Zimmerman was in a fight for his life with Martin slamming his head against a concrete sidewalk and straddling him in a mixed-martial arts maneuver known as "ground and pound."
Martin plotted and initiated the fight with Zimmerman when he instead could have returned to the townhome he was visiting after he believed Zimmerman was following him.
The testimony of Jeantel was influenced by the fact that she was first interviewed by an attorney for Martin's family, not detectives, and then talked to prosecutors in the home of Martin's mother.
Lead detective Chris Serino said he didn't find any major inconsistencies in Zimmerman's story.
Forensic pathologist Dr. Vincent DiMaio said the forensic evidence was consistent with Zimmerman's description of how he shot Martin.
Martin's father, Tracy, initially said he wasn't sure if it was his son screaming for help on 911 tapes that captured the fight between Martin and Zimmerman.
Martin didn't have Zimmerman's blood on his hands because it was washed off in the rain due to coroner workers not properly covering his hands.