NEW YORK (CBSNewYork/AP) — There will be no federal charges in connection with the 2012 fatal shooting of an unarmed black teenager by a white New York City police officer.

The U.S. Attorney’s office said it is closing its investigation into the shooting death of Ramarley Graham because there is “insufficient evidence” to meet “the high burden of proof” needed for a federal criminal civil rights prosecution.

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“To prove a violation of the federal criminal civil rights statute, prosecutors must establish, beyond a reasonable doubt, that a law enforcement officer willfully deprived an individual of a constitutional right,” a news release from the office of Manhattan U.S. Attorney Preet Bharara explained. “Neither accident, mistake, fear, negligence nor bad judgment is sufficient to establish a federal criminal civil rights violation.”

The decision infuriated the Rev. Al Sharpton, who said he spoke to Graham’s mother.

“She’s very much heartbroken, but also very determined to continue the fight,” Sharpton said. “She wants the officers fired.”

Sharpton himself also called on City Hall to fire the officers.

Graham’s father, Frank Graham, told the New York Daily News that Tuesday’s decision was “heartbreaking” and “frustrating.”

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“But we’ll just move onto the next fight — which is firing the officers immediately,” he said.

The case generated heated anger four years ago, as CBS2 Political Reporter Marcia Kramer recalled.

Graham was 18 when he was shot in the bathroom of his Bronx home by an officer who had barged inside during a drug investigation in February 2012.

Prosecutors have said police first encountered Graham when they spotted him and two other people walking into a Bronx bodega on the afternoon of Feb. 2 of that year, and then immediately walking out. The officers, who were conducting a street narcotics investigation, said they saw Graham adjusting his waistband and told fellow officers they believed he had a gun.

Police followed him to his Bronx home. An officer made his way into the home, forced his way into a bathroom and shot Graham once.

Richard Haste, the officer who shot Graham, has said in a court filing that he fired because he believed Graham had a gun and was about to shoot. No weapon was ever found.

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