As demonstrators from New York to California rally against the acquittal of George Zimmerman in the death of Trayvon Martin, his attorney is voicing concern for his safety.

On Sunday protests are planned in cities including Boston, New York City, Chicago and San Francisco, a day after a jury found the former neighborhood watch volunteer not guilty.

After Saturday's verdict, police, officials and civil rights leaders urged peace and told protesters not to resort to violence. While the defense said they were thrilled with the outcome, Zimmerman's attorney Mark O'Mara suggested his safety would be an ongoing concern.

"There still is a fringe element that wants revenge," O'Mara said. "They won't listen to a verdict of not guilty."

His brother said the former neighborhood watch volunteer was still processing the reality that he wouldn't serve prison time for the killing, which Zimmerman, 29, has maintained was an act of self-defense. A jury found him not guilty of second-degree murder late Saturday night and declined to convict him on a lesser charge of manslaughter.

However, with many critics angry over his acquittal, his freedom may be limited.

"He's going to be looking over his shoulder the rest of his life," Robert Zimmerman Jr. said during an interview on CNN.

Martin's killing in February 2012 unleashed debate across the U.S. over racial profiling, self-defense and equal justice. Protesters nationwide lashed out against police in the Orlando suburb of Sanford as it took 44 days for Zimmerman to be arrested. Many, including Martin's parents, said Zimmerman had racially profiled the unarmed black teen. Zimmerman identifies as Hispanic.

Six anonymous female jurors considered nearly three weeks of often wildly conflicting testimony over who was the aggressor on the rainy night the 17-year-old was shot while walking through the gated townhouse community where he was staying and where Zimmerman lived.

Jurors were sequestered during the trial, and they deliberated more than 15 hours over two days before announcing late Saturday night that they had reached a verdict. The court did not release the racial and ethnic makeup of the jury, but the panel appeared to reporters covering selection to be made up of five white women and a sixth who may be Hispanic.

Those watching reacted strongly when the verdict was announced. Martin's mother and father were not in the courtroom when it was read; supporters of his family who had gathered outside yelled "No! No!" upon learning of the verdict.

Andrew Perkins, 55, a black resident of Sanford, angrily asked outside the courthouse: "How the hell did they find him not guilty?"

"He killed somebody and got away with murder," Perkins shouted, so angry he shook, looking toward the courthouse.

However Zimmerman also had some supporters outside the courthouse, including Cindy Lenzen, 50, of Casslebury, and her brother, 52-year-old Chris Bay, who stood watching others chant slogans such as, "the whole system's guilty."

Lenzen and Bay — who are white — called the entire case "a tragedy," especially for Zimmerman.

"It's a tragedy that he's going to suffer for the rest of his life," Bay said. "No one wins either way. This is going to be a recurring nightmare in his mind every night."

Before a special prosecutor assigned to the case ordered Zimmerman's arrest, thousands of protesters had gathered in Sanford, Miami, New York and elsewhere, many wearing hoodies like the one Martin had on the night he died. They also carried Skittles and a can of iced tea, items Martin had in his pocket. President Barack Obama also had weighed in, saying that if he had a son, "he'd look like Trayvon."

Despite the racially charged nature of the case, race was barely mentioned at the trial.

"This case has never been about race or the right to bear arms," Corey said. "We believe this case all along was about boundaries, and George Zimmerman exceeded those boundaries."

One of the few mentions of race came from witness Rachel Jeantel, the Miami teen who was talking to Martin by phone moments before he was shot. She testified that he described being followed by a "creepy-ass cracker" as he walked through the neighborhood.

Jeantel gave some of the trial's most riveting testimony. She said she overheard Martin demand, "What are you following me for?" and then yell, "Get off! Get off!" before his cellphone went dead.

The jurors had to sort out clashing testimony from 56 witnesses in all, including police, neighbors, friends and family members.

Based on reporting by The Associated Press.

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