Defendant Roy Oliver (R) and his defense attorney Bob Gill speak after seeing a question from the jury indicating they can't reach a unanimous verdict during the ninth day of the trial at the Frank Crowley Courts Building on August 28, 2018 in Dallas, Texas. (Photo: VCG)

A Texas jury sentenced a former police officer to 15 years in prison Wednesday night for the shooting death of an unarmed African-American teen in a Dallas suburb.

The jury deliberated for 12 hours before deciding the fate of former Balch Springs officer Roy Oliver. In addition to the prison term, it imposed a fine of $10,000.

Roy Oliver fired five bullets into a car full of teens last year, killing Jordan Edwards while responding to a call of underage drinking at a party in a Dallas suburb. 

The unarmed Edwards and four others were leaving the party after hearing gunfire, which had come from another nearby location. Oliver fired a rifle into the car, hitting the teen in the head.

The trial jury also found the officer, who was reportedly fired from his job, not guilty of two aggravated assault charges. 

Tearful family members could be seen embracing during a court recess after the verdict was read on Tuesday. 

"I'm happy, very happy. It's been a long time," the slain teen's father Odell Edwards told assembled news media. 

The trial resumed shortly after with the sentencing phase.

The jury had deliberated for just two days before returning the rare conviction of a police officer in a high-profile shooting. 

Similar convictions in other cases have proven mostly elusive, illustrating the difficulty of convicting officers in deadly encounters where split-second decisions are made.

Edwards family attorney Daryl Washington said the case was "about every African American, unarmed African American, who has been killed and who has not gotten justice."

- 'No other option' -

Police originally said Oliver opened fire because the car was backing up aggressively toward him, but the department changed its account after viewing bodycam footage, saying the car was driving away when Edwards was shot.

At trial, Oliver testified that he fired because the car was driving toward his partner. 

"I had to make a decision," Oliver testified. "This car is about to hit my partner, there are threats inside the car and when lethal force is being presented toward us, I had no other option but to use lethal force."

But Oliver's partner Tyler Gross testified at trial that he had not felt in danger, according to US media reports.

"I just wanted them to stop," Gross said, according to WFAA TV. "I was not in fear at that point."

The Dallas County Sheriff's Office said in a statement announcing Oliver's arrest warrant last year that evidence suggested the police officer "intended to cause serious bodily injury." 

The shooting was among a growing list of similar cases in which African Americans were killed by white police officers.

The high-profile incidents, often accompanied by official or eyewitness video footage, have fueled outrage across the United States and given rise to the Black Lives Matter movement.

Oliver was the first on-duty Texas officer in more than 40 years to be convicted in a shooting death, according to the Fort Worth Star-Telegram. 

The Texas chapter of the American Civil Liberties Union hailed the conviction for sending "a powerful message."

"There is a long history in this country of failing to hold law enforcement responsible for even the gravest abuses of power," the group's Sharon Watkins Jones said in a statement.