Last updated at 6:15 p.m.

The now-fired Balch Springs police officer who fatally shot 15-year-old Jordan Edwards took the stand Thursday to try to spare himself from a murder conviction.

Roy Oliver is charged with killing the ninth-grader in April 2017 as he sat in a car leaving a party.

Moments before Oliver fired, gunshots had rung out in the neighborhood. They turned out to have come from the parking lot of a nearby nursing home and had nothing to do with Jordan or the vehicle he was in.

But Oliver, 38, testified that he felt he had to shoot because he feared a fellow officer was in danger of being run over by the Chevrolet Impala. The car had come to a stop for a moment but then moved forward, he told jurors.

"I had to make a decision. This car is about to hit my partner," Oliver told jurors. "I had no other option."

Prosecutors say neither he nor his partner were ever in danger and Oliver never should have fired into the car. Oliver fired five times and continued to shoot as the car, driven by Jordan's 16-year-old brother, drove away. Jordan was hit in the back of the head.

As he testified, Oliver gently swiveled back and forth in a brown leather chair on the witness stand as he answered questions from his attorneys. Oliver told jurors he was sickened by what he'd done even though he believed that he acted appropriately given what he knew when he pulled the trigger five times.

He was conversational on the stand. He didn't lose his temper. At least two jurors nodded as he spoke.

Oliver said he didn't know much about Balch Springs when he started there -- just that the city needed police officers because the department was often shorthanded.

The police department is majority white, while minorities make up 80 percent of

population. Oliver is white. Jordan, a ninth-grade football player, was black.

The day of the shooting, Oliver testified, nothing out of the ordinary had happened. He'd worked a 12-hour shift the previous day and slept five or six hours.

He got in an hour before his 6 p.m. shift, just as he usually did. He made sure his car had gas and was ready to go when his workday officially began, he said.

Oliver and another officer, Tyler Gross, responded to the call about intoxicated kids in the street, Oliver said, so he followed Gross onto the street where the party was. Oliver was serving as backup to Gross, he said.

1 / 8Fired Balch Springs police officer Roy Oliver, who is charged with the murder of 15-year-old Jordan Edwards, prepares to give testimony during the sixth day of his trial.(Rose Baca / Staff Photographer) 2 / 8Roy Oliver speaks after being asked what he felt once realizing who he had shot was not a threat.(Rose Baca / Staff Photographer) 3 / 8Odell Edwards, the father of Jordan Edwards, puts his head down while listening to testimony from fired Balch Springs police officer Roy Oliver.(Rose Baca / Staff Photographer) 4 / 8Defense attorney Jim Lane questions Roy Oliver, who is charged with the murder of 15-year-old Jordan Edwards.(Rose Baca / Staff Photographer) 5 / 8Fired Balch Springs police officer Roy Olive testified that he was worried about his partner's safety when he fired his rifle.(Rose Baca / Staff Photographer) 6 / 8Defense attorney Bob Gill gives an opening argument for Roy Oliver.(Rose Baca / Staff Photographer) 7 / 8Roy Olive motions with his hands when describing his field of vision on the car that Jordan Edwards was in.(Rose Baca / Staff Photographer) 8 / 8Judge Brandon Birmingham listens to defense attorney Bob Gill during the sixth day of the murder trial of fired Balch Springs police officer Roy Oliver.(Rose Baca / Staff Photographer)

Partygoers were streaming out of the house as the officers arrived. No one was stumbling or disrespectful, he said. Gross left the red and blue lights on his car flashing. Oliver said he left on only the steady, nonflashing lights on the end of the bar on top of his patrol car.

Gross went inside and Oliver checked the outside of the house for alcohol and safety issues before heading in. Once he got inside, the officers heard gunshots.

"Oh no, active shooter," Oliver said about what he immediately thought.

He said he was concerned because the officers' presence had pushed people out of the home, some in the direction of the shots.

The officers ran outside, and Oliver said people were screaming and he asked dispatch for help. In such situations, officers "can get rattled," he said.

He was trying to assess how many shooters there were and what they were firing with, he testified. He grabbed his rifle from his patrol car because he didn't feel his pistol was adequate.

It was later determined that no alcohol was served at the party, and no one in the car with Jordan had any weapons.

Gross headed toward the gunfire, Oliver said, and he readied his rifle to be able to fire.

It was dark and Oliver walked toward Gross' voice.

Gross "got on the radio and called out a license plate," Oliver said. Gross had walked past other cars and didn't read the plate numbers.

"There's something going on with this car and I've got to get up there to help him with it," Oliver recalled thinking.

Oliver ran toward Gross and testified he heard Gross yell, "Stop the … car."

"I thought he had located the shooter or shooters or at least has some type of information toward it," Oliver said.

As Oliver got closer to testifying about the moment he fired his rifle, Jordan's stepmother, Charmaine Edwards, bowed her head and leaned forward. Jordan's father, Odell Edwards, kept looking ahead, watching Oliver on the stand.

The car backed up, going up an incline of two to two-and-a-half feet. The car drove from an east-west street, Baron Drive, to the north-south street Shepherd Lane.

As Oliver ran toward Shepherd, he saw Gross — who had his weapon out — trying to shine a light into the car.

A streetlight shone on the Chevrolet Impala, causing a reflection that he said kept him from getting a good view of what was in the car. He said he could see two people inside but not many details other than a silhouette moving.

Oliver said he had no idea who was in the car. He said he "heard a pop, a possible gunshot from inside the car."

He made the decision to shoot "when the vehicle was moving toward my partner," he said. He was "trying to stop threats." He continued to fire as the car drove away. Jordan was struck in the back of the head.

His first thought after firing, Oliver said, was to make sure Gross was OK.

Defense attorneys asked Oliver whether he asked about Gross as cover so it would be picked up by the microphone on the body camera.

"I'm not that fast," Oliver replied. "I don't think anyone is in that situation."

Just 54 seconds had passed from the first shots at the nursing home to when Oliver shot his rifle.

Afterward, Oliver said, "I was in shock. I was in shock for days."

The realization of who he had shot was horrifying, he said. He checked Jordan's pulse and felt nothing.

"It was a

to the gut," Oliver said, calling it "sickening" — a bad situation that kept getting worse.

"My heart sank. For a minute there, it was hard to breathe."

Jordan's family walked out as he spoke, but jurors were riveted by his account of events. They turned down a break when state District Judge Brandon Birmingham offered one.

Oliver's bald head shone under the lights of the courtroom. On the lapel of his charcoal suit, he wore a puzzle-piece-shape pin that says "Autism." His young son, Tab, has autism

'Sick to my stomach'

Oliver said if he knew then what he knows now, he never would have fired at the car.

"If I had all that information, no."

Oliver said two things could have prevented the shooting: if witnesses who knew what happened had said the shots hadn't been fired from that car, or "if the driver" — Jordan's brother, 16-year-old Vidal Allen — "would have listened and stopped."

He said he is "sick to my stomach, heartbroken" about the shooting.

On cross-examination, Mike Snipes, the top prosecutor under District Attorney Faith Johnson, asked whether Oliver meant to kill or injure the driver.

"Stop the threat, correct," Oliver said.

"Do you admit you shot an innocent bystander?" Snipes asked.

"He was a perceived threat at that time," Oliver said.

Snipes then showed a photo on large screens in the courtroom of Jordan slumped over, bloody and already dead, next to a red Fanta bottle. But not before suggesting Jordan's family leave before he showed the photo. His stepmother had already left but the rest of the family filed out of the courtroom.

Oliver's voice cracked slightly and he stared ahead as he said yes, he had been the person who killed Jordan.

Previous incident

The defense asked Oliver about an incident when his truck was rear-ended two weekends before Jordan's death. Prosecutors have sought to introduce witnesses to say Oliver pointed a gun at them after the crash. The judge said no, but his ruling didn't preclude defense attorneys from asking about the incident.

Now that the defense has introduced the matter of the crash, prosecutors will be able to ask about it — but now have heard about it from Oliver's point of view first. Oliver has been indicted on aggravated assault charges from the incident.

Oliver's wife and then-1-year-old son, who was napping, were in the vehicle with him when they were struck at a red light in Dallas. His son began screaming and crying, Oliver said, and he got out of the truck and told his wife to call 911.

"'I pushed the brakes, it's not my fault,'" he said he heard someone in the car that struck him say.

He was off duty and had a backup weapon and badge on his waist, under a T-shirt. He lifted his shirt, he said, to visibly identify himself as a police officer.

He said he asked the driver to put her hands on the steering wheel so he could see them.

Oliver said he then got his gun out in a "low ready position" to quicken his response time if he needed to react. He said he walked toward the car and the woman was still yelling. There were two juveniles in the back of her car, he said.

The other driver had an ID card but not a driver's license, Oliver testified.

Oliver said that after Dallas police came to the crash, he called his supervisor to tell him he displayed his weapon.

Dallas police did not pursue charges. The case went nowhere until after Oliver shot Jordan.

What is reasonable?

Defense attorney Bob Gill, in his opening statement to the jury, told jurors that they had to consider the shooting from Oliver's point of view, not anyone

when they deliberate whether "Roy Oliver was reasonable" when he fired at the car.

Gill told the jury that Jordan's death was a tragedy for the Edwards family and the

and that it is a tragedy anytime an officer must make the decision whether to shoot.

After Oliver's testimony, the defense called their own use-of-force expert to the stand. Jay Oliver Coons, a captain with the Harris County Sheriff's Office, contradicted the prosecution's use-of-force expert, who said the shooting wasn't justified.

Coons, who reviews use-of-force cases at the sheriff's department and for his own business, said, "Officer Oliver's actions on the night in question were reasonable."

Army service

Oliver also told jurors about his service in the Army and his deployment to Iraq in 2004.

He told jurors he was unprepared for what he saw when he arrived. Within 24 hours, his unit was attacked by mortar fire. He and other soldiers lived in what were essentially shipping containers with beds and air conditioners.

"I don't think you can ever be 100 percent prepared for that," Oliver testified.

He struggled to control his emotions as he told jurors about a supply sergeant who was killed by a suicide bomber in the mess hall.

Oliver said he and other soldiers would have died, too, if they had not chosen to eat in a different mess hall nearby because it was serving bacon cheeseburgers. He said he eats a bacon cheeseburger every Dec. 21, the anniversary of the attack.