NEW YORK (Reuters) - A former New York City police officer avoided prison on Tuesday for the killing of an unarmed black man in an unlit stairwell, prompting demonstrations outside a Brooklyn courthouse.

Protesters support former New York Police Officer Peter Liang outside a Brooklyn courthouse before his sentencing for manslaughter in the killing of Akai Gurley, in New York April 19, 2016. REUTERS/Joseph Ax

State Supreme Court Justice Danny Chun sentenced Peter Liang to 800 hours of community service, after prosecutors recommended six months of home confinement.

Liang, a rookie who lost his badge after his conviction, had faced up to 15 years for his manslaughter conviction in the death of Akai Gurley, 28.

The officer was patrolling the darkened stairs inside a public housing building in Brooklyn on Nov. 20, 2014, when he fired a single shot that he testified was accidental. The bullet ricocheted off a wall and struck Gurley in the chest as he walked one floor below.

Before imposing the sentence, Chun reduced Liang’s manslaughter count to the lesser felony of criminally negligent homicide, finding prosecutors failed to prove Liang “consciously disregarded” the risk of causing another person’s death.

“There is no evidence, circumstantially or otherwise, that the defendant was aware of Akai Gurley’s presence,” he said.

As Chun announced Liang would not face prison, some of Gurley’s supporters in the courtroom began sobbing.

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The shooting fueled nationwide protests over law enforcement’s use of excessive force on minorities. But the case differed from many other high-profile incidents that helped intensify the Black Lives Matter movement. Liang, who is Chinese-American, was not accused of deliberately killing Gurley.

Chinese-American activists organized their own rallies after his conviction, claiming Liang was a scapegoat for police misconduct. Chun said he had received 40,000 letters in support of Liang, though many were identical.

Outside the courthouse, dueling groups of protesters - one supporting Liang, the other Gurley’s family - stood on opposite sides of the street, holding signs and chanting.

Both prosecutors and defense lawyers on Tuesday urged Chun not to hold Liang responsible for the actions of other officers.

“This simply is not a case of police brutality,” said Assistant District Attorney Joseph Alexis. “This prosecution has always been about justice; it’s not about revenge.”

Members of Gurley’s family have criticized Brooklyn District Attorney Kenneth Thompson for recommending no prison time.

In a statement, Thompson said Liang would have to “always live with the fact that he recklessly caused Mr. Gurley’s death.”

Before he was sentenced, Liang apologized to Gurley’s family in court and said he never intended to fire the fatal bullet.

“My life is forever changed,” he said.

Liang testified at trial that he did not realize the bullet had hit anyone until he saw Gurley’s girlfriend desperately trying to revive him. The officer claimed a noise startled him, causing his finger to pull the trigger.

But prosecutors said he acted recklessly in drawing his weapon and discharging a round.