In San Francisco and Los Angeles - where an earlier protest was dispersed with beanbag rounds - police closed streets as protesters marched to condemn Zimmerman's acquittal. In Los Angeles, around 200 demonstrators gathered for a vigil in one of the city's African-American neighbourhoods, Leimert Park. Police in Oakland, California, said a small crowd took to the streets, with some breaking windows, spraying anti-police graffiti and burning US and California state flags.
In Florida, about 200 protesters marched with signs that said "racism is not dead" and "who's next?"
Zimmerman, 29, is now a free man, but the Justice Department said it is looking into Martin's death to determine whether federal prosecutors will file criminal civil rights charges against his killer.
With many critics angry over Zimmerman's acquittal, his freedom may be limited. He may also face civil lawsuits from Martin's family. "He's going to be looking over his shoulder the rest of his life," his brother, Robert Zimmerman told CNN.
President Barack Obama called Martin's death a tragedy for America but asked that everyone respect calls for calm reflection. "I know this case has elicited strong passions. And in the wake of the verdict, I know those passions may be running even higher. But we are a nation of laws, and a jury has spoken."
The Justice Department opened an investigation into Martin's death last year but stepped aside to allow the state prosecution to proceed.
The department yesterday said the criminal section of its civil rights division, the FBI and the local US Attorney's office are continuing to evaluate the evidence. Experience has shown it's not easy getting convictions in such high-profile prosecutions. Alan Vinegrad, a former US Attorney, said federal prosecutors "would have to show not only that the attack was unjustified, but that Mr Zimmerman attacked Mr Martin because of his race and because he was using a public facility, the street."
The case
Was race important?
George Zimmerman's opponents believe he followed Trayvon Martin because he was a young black man wearing a hoodie. Zimmerman told police he had seen someone and told the dispatcher: "F****** punks. These assholes, they always get away." He was ruled to have shot Trayvon in self-defence. Cuts and bruises on Zimmerman's head showed the pair had fought.
So is self-defence plausible?
On a 911 call made by one of Zimmerman's neighbours as the pair were fighting, a voice pleads for help. The prosecution said this was Trayvon. The defence said it was Zimmerman. Neither side was able to prove who was speaking.
What about the witnesses?
Trayvon's friend, Rachel Jeantel, on the phone with him not long before he died, said he kept complaining that a man was watching him. She heard Trayvon tell someone to "get off" before the line went dead. An expert defence witness claimed the angle of the shot that killed Martin proved he was on top of Zimmerman.
- Independent, AP
