By Valerie Volcovici

ST. LOUIS (Reuters) – A Missouri judge on Friday found a former St. Louis police officer not guilty of murder in the shooting death of a black man after a car chase in 2011, prosecutors said.

Officials feared the verdict could set off violent protests, as have similar deadly cases involving police and minorities around the United States in recent years.

Jason Stockley, 36, who is white, had been charged with first-degree murder, accused of intentionally killing Anthony Lamar Smith, 24, and planting a gun in his car. Stockley, who was arrested in May 2016, testified he acted in self-defense.

Judge Timothy Wilson’s highly anticipated ruling was announced Friday, more than five weeks after the bench trial ended.

Prosecutor Kimberly Gardner said in a statement she was disappointed with the verdict and believed she had presented proof that Stockley intended to kill Smith.

“However, in this case it was the judge’s duty to evaluate the evidence and deliver his findings,” she said. “That’s how our system works.”

Killings of unarmed black people by U.S. police in recent years triggered widespread protests and activists promised disruptive demonstrations if Stockley was acquitted.

St. Louis and state officials were braced for violent protests and racial tensions like those that followed the 2014 fatal shooting by police of unarmed black teenager Michael Brown in Ferguson, near St. Louis.

Missouri Governor Eric Greitens on Thursday put the National Guard on standby. Some schools called off classes and some events were postponed, according to local media.

Christina Wilson, Smith’s fiancée, pleaded at a news conference on Thursday evening for protesters to avoid violence if they demonstrate.

The verdict in St. Louis follows high-profile mistrials or acquittals of police officers charged in shootings in Ohio and Minnesota this year.

Authorities say Smith tried to flee from Stockley on Dec. 20, 2011. During a pursuit, Stockley could be heard saying on an internal police car video that he was going to kill Smith, prosecutors said.

Stockley, riding in the passenger seat of a patrol vehicle with his personal AK-47 in one hand and department-issued weapon in the other, shot at Smith’s car, according to St. Louis Circuit Attorney’s Office spokeswoman Susan Ryan and charging documents. Stockley and his partner chased Smith at speeds exceeding 80 miles per hour (129 kph), the documents said.

At Stockley’s direction, the driver of the police car slammed into Smith’s vehicle and they came to a stop. Stockley then approached Smith’s car and shot him five times, court documents said.

Stockley’s lawyers said he fired in self-defense because he believed Smith was reaching for a gun but prosecutors said the only gun recovered from the scene had only Stockley’s DNA on it.

Stockley, who maintained his innocence, waived his right to a jury trial, allowing the judge to decide. He left the St. Louis Metropolitan Police Department in 2013, and additional evidence led to his arrest last year.

Smith’s family in 2013 settled a lawsuit filed against the city for $900,000, the family’s lawyer, Albert Watkins, said.

(Reporting by Suzannah Gonzales and Chris Kenning; Editing by Bill Trott)