Jason Stockley
Jason Stockley, an ex-St.Louis police officer, is pictured in this police handout photo, Aug. 10, 2017. Harris County Sheriff's Office/Handout via Reuters/File Photo

Protests erupted on Friday in St. Louis, Missouri, after former police officer Jason Stockley was found not guilty of first-degree murder in the 2011 shooting death of black motorist Anthony Lamar Smith, reports said.

The shooting happened on Dec. 20, 2011, as Stockley and his partner, Brian Bianchi, chased Smith over a drug deal. But Stockley was not accused of alleged involvement in the shooting death until May 2016, when the then-circuit attorney, Jennifer Joyce, charged him with first-degree murder.

The footage captured on dashcam of the police car and a cell phone video of the shooting aftermath played a key role in the trial that began Aug. 1, CNN reported.

Amid the aftermath, Stockley, 36, resigned from the city police department in 2013 after serving as an officer for five years. According to St. Louis Post-Dispatch, he had a military career prior to that and had graduated from the U.S. Military Academy at West Point. Stockley had also been on a tour to Iraq during his time in the army and chose to be a police after that because “it’s based on a foundation of service," he had said.

A report by Stockley stated he and his partner tried to stop Smith after witnessing a suspected drug transaction in a parking lot of a restaurant. When Bianchi told Stockley that Smith was reaching for a weapon, Stockley went to him with his department-issued handgun along with his personal AK-47 pistol — even though carrying the latter was against the department’s policy.

The officer fired several shots at the vehicle when Smith tried to speed away, knocking Stockley sideways. Both the officers chased Smith in their car at speeds of more than 80 mph and at some point, the vehicle crashed into Smith’s, said the report.

According to unconfirmed reports, Smith was alive when the officers approached him after the crash. Stockley asked him to show his hands when he thought the suspect was reaching for a gun. Stockley then fired at Smith in the chest, killing him on the spot. Prosecutors said Stockley also planted evidence after DNA analysis showed the gun, which Stockley said belonged to Smith, did not show any signs of the Smith's DNA.

However, in his ruling, St. Louis Circuit Judge Timothy Wilson said the state failed to prove that Stockley did not act in self-defense. "This Court... is simply not firmly convinced of the defendant's guilt," he stated. "Agonizingly, this Court has (pored) over the evidence again and again," including the video footage "innumerable times."

In an interview with Post-Dispatch after the acquittal, Stockley said he felt like “a burden has been lifted.”

“The taking of someone’s life is the most significant thing one can do, and it’s not done lightly. … My main concern now is for the first responders, the people just trying to go to work and the protesters. I don’t want anyone to be hurt in any way over this,” he said.

Immediately after the verdict, agitators took to the streets to mark their protest against the ruling. The largely peaceful protests turned violent towards the evening and around 1,000 protesters gathered in front of the home of St. Louis Mayor Lyda Krewson. They could be seen throwing rocks and breaking windows.

Thirteen people were arrested and four officers suffered injuries in the protests, according to Washington Post.