A St. Louis County grand jury has brought no criminal charges against Darren Wilson, a White police officer who fatally shot Michael Brown, an unarmed African-American teenager, more than three months ago in nearby Ferguson.

The decision was announced Monday night by the St. Louis County prosecutor, Robert P. McCulloch, at a news conference packed with reporters from around the world. The killing on a residential street in Ferguson set off civil unrest—and a national debate—fueled by protesters’ outrage over what they called a pattern of police brutality against young Black men.