Protests over Florida verdict

Calling 17-year-old Trayvon Martin's death in February 2012 a tragedy, "not just for his family, or for any one community, but for America," Obama appealed for people to remain calm after a court in Sandford, Florida, found that Martin's killer was acting in self-defense.

"I know this case has elicited strong passions," Obama said in a statement. "And in the wake of the verdict, I know these passions may be running even higher."

Americans spontaneously marched in Philadelphia, Atlanta, Florida capital Tallahassee, and US capital Washington. In New York, several thousand marched to Times Square as police lay in wait for them to step out of line. Many in the multi-racial crowd brandished signs bearing a portrait of Martin, and, despite temperatures that have neared 40 degrees Celsius lately (about 100 degrees Fahrenheit), wore hooded sweatshirts similar to one the 17-year-old had on the night of his death.

Chants included "The people say guilty!" and "No justice, no peace!" One sign urged, "Jail racist killers, not black youth." Another declared: "We are all Trayvon. The whole damn system is guilty." At least one marcher wore a T-shirt proclaiming: "I'm black. Please don't shoot."

'Shoot first' laws

Zimmerman's supporters believe he killed Martin within the boundaries of Florida's "Stand Your Ground" law, which allows deadly force for self-defense. Many, though, consider the case a murder sparked by racism, believing that Zimmerman, a volunteer neighborhood watchman, initiated the confrontation.

The jurors deliberated for 16 hours over two days before finding Zimmerman not guilty of second-degree murder and manslaughter, owing to the protection of "Stand Your Ground." As police had believed the unarmed teenager's was killing within the bounds of the law, Zimmerman, now 29, initially remained free for weeks after shooting the boy in February 2012.

"'Shoot first' laws like those in Florida can inspire dangerous vigilantism and protect those who act recklessly with guns," said New York Mayor Michael Bloomberg, who has spearheaded weapons-control legislation unpopular in states such as the one where the teenager was killed. "The tragic death of Trayvon Martin, an unarmed child attempting to walk home from the store, will continue to drive our efforts," Bloomberg added.

Further investigation

After the verdict, Trayvon's parents, Tracy Martin and Sybrina Fulton, who did not sit in the courtroom while the jury announced the fate of their son's killer, responded quickly on Twitter.

"Even though I am broken hearted my faith is unshattered I WILL ALWAYS LOVE MY BABY TRAY," Tracy Martin, the boy's father, wrote on Twitter.

"Lord during my darkest hour I lean on you," wrote Fulton, the boy's mother. "You are all that I have. At the end of the day, GOD is still in control ... I will love you forever Trayvon!!!"

Although the defendant was cleared, the US Justice Department has announced that it will look into Martin's death to determine whether federal prosecutors will file criminal civil rights charges against Zimmerman. He may also face civil lawsuits from Martin's family.

In a statement released on Sunday, the Justice Department announced that it would determine whether "the evidence reveals a prosecutable violation of any of the limited federal criminal civil rights statutes within our jurisdiction."

mkg/ccp (Reuters, AFP, dpa, AP)