Story highlights "We will never, ever forget what happened to our son," Trayvon Martin's family says

George Zimmerman was acquitted on a criminal charge of second-degree murder

Federal authorities had investigated whether to charge him based on hate crime law

Washington (CNN) No civil rights charges will be brought against George Zimmerman in the February 2012 shooting death of Trayvon Martin, the U.S. Justice Department announced Tuesday, citing what it said was insufficient evidence.

Zimmerman was acquitted of criminal charges in 2013 in the killing of the 17-year-old Martin, who was black.

"Though a comprehensive investigation found that the high standard for a federal hate crime prosecution cannot be met under the circumstances here, this young man's premature death necessitates that we continue the dialogue and be unafraid of confronting the issues and tensions his passing brought to the surface," Attorney General Eric Holder said in a news release. "We, as a nation, must take concrete steps to ensure that such incidents do not occur in the future."

Justice Department prosecutors and officials from the FBI met with Martin's family on Tuesday to inform them of the decision, the department said.

In a Tuesday afternoon statement, the family thanked the Justice Department for its investigation and "millions of people around the world" who supported them.

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