A Florida jury on Saturday found George Zimmerman not guilty in the shooting death of unarmed black teenager Trayvon Martin, in a case that sparked a national debate on race and guns.
The panel of six women deliberated more than 16 hours over two days until nearly 10 p.m. on Saturday (0200 GMT Sunday) before delivering the verdict, which drew immediate condemnation from some civil rights groups.
Zimmerman appeared stoned-faced as the verdict was announced, but then showed a slight smile of relief. His parents embraced each other and his wife was tearful.
Zimmerman, 29, said Martin, 17, attacked him on the night of Feb. 26, 2012, in the central Florida town of Sanford. Prosecutors contend the neighborhood watch coordinator in his gated community was a "wannabe cop" who tracked down the teenager and shot him without justification.
The jury could have convicted him of second-degree murder or manslaughter.
"Today, justice failed Trayvon Martin and his family," Roslyn M. Brock, chairman of the National Association of Colored People, said in a statement.
"We call immediately for the Justice Department to conduct an investigation into the civil rights violations committed against Trayvon Martin. This case has re-energized the movement to end racial profiling in the United States."
The news also drew angry shouts from some of the dozens of demonstrators who had gathered outside the courtroom during the day in support of Martin's family. His parents were not in the court during the reading of the verdict.
Civil rights leader Jesse Jackson tweeted within minutes of the acquittal: "Avoid violence, it will lead to more tragedies. Find a way for self construction not deconstruction in this time of despair."
What happened in Sanford that February night may never have gone beyond the back pages of a local newspaper if police had immediately arrested Zimmerman.
But he walked free for more than six weeks after the shooting, because police believed his claim of self-defense, triggering protests and cries of injustice across America.
It also drew comment from President Barack Obama, forced the resignation of Sanford's police chief, and brought U.S. Justice Department scrutiny to this town of 54,000 residents not far from Disney World in Orlando.