A jury acquitted George Zimmerman on the killing of teenager Trayvon Martin today in a case that sparked national debate over racial profiling, civil rights and self-defense laws.

The six-women jury handed over their verdict to the judge after deliberating for more than 16 hours over two days at around 10 p.m. Saturday. Zimmerman, 29, shot Martin, 17 in a Sanford, Florida neighborhood last year and faced a second-degree murder charge for which he could have been sentenced to life in prison.

"As painful as it may be, though, acquitting George Zimmerman was the only verdict the jury could logically reach. The state simply didn't prove second-degree murder. Or manslaughter," wrote The Orlando Sentinel columnist Beth Kasaab who has been following the case for months.

The verdict stirred outrage among civil rights groups. The New York Times reports that outside the courtroom on Saturday, as much as a hundred protesters were gathered waved placards and chanted "No Justice, no peace!"

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.

"I think the prosecution of George Zimmerman was disgraceful," said his attorney Don West. "As happy as I am for George Zimmerman, I'm thrilled that this jury kept this tragedy from becoming a travesty."

Martin's parents were not in the court during the reading of the verdict, but his father, Tracy Martin, later tweeted that his son would have been proud of the fight put up for him.

"Even though I am broken hearted my faith is unshattered," he wrote. "Together can make sure that this doesn't happen again."

Zimmerman, who is white and Hispanic, said Martin, 17, attacked him on the night of February 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, which would have carried a sentence of up to life in prison, or manslaughter.

"Today, justice failed Trayvon Martin and his family," Roslyn Brock, who chairs the National Association for the Advancement 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."

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."

(Reuters contributed to this report.)

Tags: George Zimmerman Trial