St. Louis, November 25 (RHC)-- A grand jury in the U.S. state of Missouri has decided not to indict a white police officer for killing an unarmed Black teenager in Ferguson last summer. Ferguson police officer Darren Wilson, 28, will not face charges for the shooting death of 18-year-old Michael Brown on August 9th, according to St. Louis County prosecutor Robert McCulloch late Monday night.

The grand jury's long awaited decision was announced after darkness had fallen. Wilson can still face civil rights charges brought by the U.S. Justice Department or a civil lawsuit filed by Brown's parents.

The 12-member grand jury, including nine whites and three African Americans, had been meeting in secret for months on whether probable cause existed to bring charges against Wilson.

Rights groups have vowed to hold fresh protests if Wilson is not indicted in the killing, while the state of Missouri has been planning a massive police presence to deal with any potential violence.

Brown's death triggered weeks of protests and clashes between police and demonstrators in Ferguson. At times, the police used unnecessary and disproportionate force.