Former St. Louis police officer Jason Stockley has been found not guilty of first-degree murder in the shooting 2011 death of black motorist Anthony Lamar Smith.

On Friday (Sept. 15), St. Louis Circuit Judge Timothy Wilson wrote in his ruling that "This Court, in conscience, cannot say that the State has proven every element of murder beyond a reasonable doubt, or that the State has proven beyond a reasonable doubt that the defendant did not act in self-defense."

St. Louis Circuit Attorney Kimberly Gardner said she was "disappointed" with the judge's decision, reports CNN.

The case stems from a December 2011 incident, in which Stockley, then a St. Louis officer, shot and kill Anthony Lamar Smith during a police chase. Stockley pleaded not guilty, saying he acted in self-defense and believed Smith was reaching for a gun in his car. Prosecutors accused the officer of planting a silver revolver to justify the shooting. The ex-police officer waived his right to a jury trial, meaning the ruling was left to Judge Wilson.

Following the judge's ruling, people gathered outside of the courthouse to protest. Al Watkins, an attorney for Smith's fiancée, Christina Wilson, urged people to protest -- but do it peacefully.

"What the country needs to know is, every single person in our country, we have a right to be mad," he said. "We have a right to disagree. We have a right to express our opinion. We have a right to protest. Exploit that right, don't compromise it. Stay peaceful."

Folks are also expressing outrage on social media.

"If the prosecution couldn't prove 'anything' with the evidence that the public saw and heard, then we need new prosecutors!" tweeted one user. Another person wrote, "This was the chance for #STL to show they've learned. Instead they've let a whole city down. A city they don't care about."

Read some of the reactions below.

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