Ferguson (United States) (AFP) – The U.S. policeman who shot dead an unarmed black teenager in the Missouri town of Ferguson, triggering weeks of racially-charged unrest, will not face charges, the St Louis County prosecutor said.

Robert McCulloch told reporters that a grand jury had reviewed the evidence gathered about the August shooting and “determined that no probable cause exists to file any charge against Officer Wilson.”

The family of slain black teen Michael Brown said they were “profoundly disappointed” by the grand jury’s decision, but called for calm.

“We are profoundly disappointed that the killer of our child will not face the consequence of his actions,” the Brown family said in a statement. “While we understand that many others share our pain, we ask that you channel your frustration in ways that will make a positive change.”

This breaking news story will be updated

AFP Photo/Justin Sullivan