Prosecutors in the US city of St. Louis said they will not press charges against a former police officer who shot a black teenager in 2014.
The murder of Michael Brown in Ferguson sparked weeks of protests.
It also led to the founding of the Black Lives Matter movement.
Prosecutors said a new five-month examination of the case had found insufficient evidence to press charges of murder or manslaughter against the former officer, Darren Wilson.
In 2015, the Justice Department concluded that he had shot in self-defense.
Why was Michael Brown killed?
The exact details of what happened that day continue to be disputed by the police, eyewitnesses and family members.
What is known for certain is that around noon on August 9, 2014, Mr. Wilson was driving a police car and encountered Mr. Brown and a friend walking down a street.
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- How a shooting sparked national protests
Minutes later, Mr. Brown, 18, died and suffered at least seven gunshot wounds, according to county prosecutor Bob McCulloch. His body remained on the street for four hours before being removed.
Wilson fired a total of 12 bullets, although investigators were unclear exactly how many of the 12 wounded Brown. An injury may have been a reentry wound.
Witnesses said Brown had his hands up when he was shot, but investigators said the evidence suggested this was not the case.
The nationwide protests were sparked by the murder and the decision not to charge the officer with murder. Two policemen were shot when the riots swept through Ferguson.
What is the last?
The results after further examination of the case found, once again, that Mr. Wilson should not be charged.
“Can we prove beyond reasonable doubt that a crime occurred?” The new prosecutor, Wesley Bell, said at a press conference. “The answer to that is no.”
However, Bell said the investigation could not exonerate the officer, who resigned shortly after the murder.
“There are so many points where Darren Wilson could have handled the situation differently, and if he had, Michael Brown could still be alive,” he said.
The announcement comes as protests against racism and police brutality continue after the death of George Floyd, an unarmed black man, in Minneapolis, Minnesota, in May.