The Justice Department announced Tuesday that it had closed its investigation into the shooting death of Trayvon Martin and would not bring federal civil rights charges against George Zimmerman.
The department said in a statement that it had met with Martin's family to inform them of the decision.
Attorney General Eric Holder said that while the standard for a federal hate crime prosecution could not be met, the shooting still requires the country to confront the "issues and tensions" brought to the surface by the killing.
"We, as a nation, must take concrete steps to ensure that such incidents do not occur in the future," he said.
Zimmerman was acquitted of all charges. He was charged with second-degree murder, and jurors also had the option of convicting him of the lesser charge of manslaughter. He said that he was acting in self-defense when he killed Martin, 17, during an altercation in a gated community in Sanford, Florida, on Feb. 26, 2012.
The shooting stirred a national debate about race and guns. Martin, 17, was black; Zimmerman, 31, is of white and Hispanic descent.
Federal investigators reviewed all the evidence from Zimmerman's prosecution in Florida, conducted 75 witness interviews of their own and reviewed electronic records, the Justice Department said.
Federal authorities also retained a biomechanical expert to go over Zimmerman's descriptions of the struggle and the shooting, the statement said.
In a statement, Martin's family said that it was disappointed but thanked the Justice Department for a thorough investigation.
"We remain poised to do everything in our power to help eradicate senseless violence in our communities, because we don't want any other parent to experience the unexplainable loss we have endured," the statement said. "We will never, ever forget what happened to our son, Trayvon, and will honor his memory by working tirelessly to make the world a better place."
A lawyer for Zimmerman did not immediately answer a request for comment.
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-- Erin McClam