SANFORD, Fla. -- George Zimmerman was fed up with "punks" getting away with crime and shot 17-year-old Trayvon Martin "because he wanted to," not because he had to, prosecutors argued Monday, while the neighborhood watch volunteer's attorney said the killing was self-defense against a young man who was slamming Mr. Zimmerman's head against the pavement.
The prosecution began opening statements in the long-awaited murder trial with shocking language, repeating obscenities Mr. Zimmerman uttered while talking to a police dispatcher moments before the deadly confrontation.
Mr. Zimmerman, 29, could get life in prison if convicted of second-degree murder for gunning down the Martin youth Feb. 26, 2012, as the unarmed black teenager -- wearing a hoodie on a dark, rainy night -- walked from a convenience store through the gated townhouse community where he was staying.
The case took on racial dimensions after the Martin family claimed that Mr. Zimmerman had racially profiled the teen and that police were dragging their feet in bringing charges. Mr. Zimmerman, whose mother is Hispanic and whose father is white, has denied the confrontation had anything to do with race.
The prosecutor portrayed the watch captain as a vigilante, saying, "Zimmerman thought it was his right to rid his neighborhood of anyone who did not belong."
Mr. West told jurors a different story: the Martin youth sucker-punched Mr. Zimmerman and then pounded the neighborhood watch volunteer's head against the concrete sidewalk, and that's when Mr. Zimmerman opened fire.
Mr. West said the story that the Martin youth was unarmed is untrue: "Trayvon Martin armed himself with a concrete sidewalk and used it to smash George Zimmerman's head."
The prosecutor, however, disputed elements of Mr. Zimmerman's story, including his claim that the Martin youth put his hands over Mr. Zimmerman's mouth and reached for the man's gun. Mr. Guy said none of Mr. Zimmerman's DNA was found on the teen's body, and none of the youth's DNA was on the weapon or the holster.
But Mr. West argued that crime-scene technicians didn't properly protect the teen's hands from contamination.
Two police dispatch phone calls that could be important evidence for both sides were played for the jury by the defense.
The first was a call Mr. Zimmerman made to a nonemergency police dispatcher, who told him he didn't need to be following the youth.
The second 911 call, from a witness, captures screams in the distant background from the struggle between Mr. Zimmerman and the Martin youth. The teen's parents said the screams are from their son, while Mr. Zimmerman's father contends they are his son's.
Circuit Judge Debra Nelson ruled last weekend that audio experts for the prosecution won't be able to testify that the screams belong to the Martin youth, saying the methods used were unreliable.
On Monday, one of the first witnesses for the prosecution was a custodian of police dispatch calls. During the witness's testimony, prosecutors started playing police calls Mr. Zimmerman had made in the months before he shot the teen. The defense objected, arguing the calls were irrelevant.
The judge said she would address the matter today and sent the jurors to the hotel where they are being sequestered for the duration of the trial, which could last several weeks.
Other witnesses who testified Monday included a convenience store clerk and the 911 dispatcher who took Mr. Zimmerman's call when he was following the Martin youth. The teen had gone to the convenience store to buy Skittles and a can of iced tea.