Federal prosecutors say they won't bring criminal charges in the case of an unarmed black teenager shot to death in his home by a white New York City police officer.

Manhattan U.S. Attorney Preet Bharara (bah-RAH'-rah) says Tuesday there is "insufficient evidence to meet the high burden of proof" for any federal civil rights charges in the 2012 death of Ramarley Graham.

The 18-year-old Graham was shot in the chest in a bathroom in his family's Bronx home. Officer Richard Haste said he fired because he thought he was going to be shot. But no weapons were found in the apartment.

Haste was indicted on state manslaughter charges. But charges were dismissed by a judge who said prosecutors improperly instructed grand jurors. A second grand jury declined to re-indict Haste.