Prosecutors said Zimmerman, who is charged with second-degree murder after admitting he killed the unarmed teen 16 months ago, was the one who initiated and escalated the conflict.
Zimmerman admits killing Martin, 17, but says it was self-defense after Martin turned and attacked him.
Seminole County prosecutor John Guy noted Zimmerman can be heard in the now-infamous non-emergency call he made to police defying a dispatcher's direction not to track Martin on foot.
Guy's opening line in his opening statement quoted Zimmerman on that call, describing Martin, who prosecutors said Zimmerman thought was casing the neighborhood to break into someone's home: "[Expletive] punks."
The Orlando Sentinel said Zimmerman's defense team sought to portray him in a much different light.
Defense attorney Don West told the jury of five white women and one Hispanic woman Zimmerman was a concerned resident and conscientious member of the community -- the kind of guy anyone would want as a neighbor.
West expressed sympathy for Martin's death.
"This is a sad case, of course ... A young man lost his life" and Zimmerman "is fighting for his," he said.
Zimmerman, a neighborhood watch captain who regularly called police to report disturbances in his neighborhood, maintains he killed Martin in self-defense after the teen turned and attacked him as Zimmerman pursued him through the gated community where the shooting took place.
The New York Times noted the prosecution has a high threshold to clear to prove Zimmerman's guilt. There were lots of neighbors who heard the commotion and called 911 to report the disturbance the two created but no one could actually see what happened.
A key evidentiary ruling further hampers the prosecution's case, with Judge Debra S. Nelson ruling prosecutors will not be allowed to present supposed expert testimony of one of the 911 calls that captured someone screeching for help. Prosecutors maintain the voice on the call is Martin but Nelson said the expert testimony and technology they used to make the determination aren't solid enough to present as fact to a jury.
Furthermore, the injuries Zimmerman suffered during the altercation -- a broken nose and several scrapes on his face and head -- appear to support his version of events.
Prosecutors are expected to note there was none of Zimmerman's DNA under Martin's fingernails -- normally an expected piece of evidence if someone is involved in a physical confrontation -- and that it was Zimmerman, not Martin, who escalated the conflict.
The case is being heard in Seminole County Circuit Court in Sanford, Fla., the community where the racially charged incident took place. It sparked protests across the nation after outraged members of the black community demanded justice when the circumstances of the case came to light.
The trial is expected to last two to four weeks. Zimmerman faces 25 years to life in prison if convicted on the second-degree murder charge.