DALLAS — A former Texas police officer accused of killing a black teenager was angry, out of control and "trigger happy" when he fired at a car full of teenagers while responding to a house party, a prosecutor told jurors Thursday during the ex-officer's murder trial.

Ex-Balch Springs officer Roy Oliver's actions were unreasonable on the night he fatally shot 15-year-old Jordan Edwards last year, said Michael Snipes, a Dallas County assistant district attorney. Snipes said Edwards was an "innocent child" and that his last words were "duck, get down."

Oliver, who is white, fired his gun into a moving car carrying five black teenagers while responding to a report of underage drinking at the party. Oliver has said he and his partner feared for their lives as the car sped toward them.

But Oliver's partner, Tyler Gross, testified Thursday that he did not fear for his life as the vehicle went by and that he never felt the need to fire his weapon. During opening statements, Snipes told jurors Oliver fired at the car after it passed Gross and that Gross was in no danger.

Snipes said the prosecution will also show that Edwards and others in the car had nothing to do with shots that were heard outside the house. No guns were found inside the teens' car.

Defense attorneys did not make an opening statement on Thursday. They have previously said Edwards' death was a tragedy but evidence would show Oliver "reacted properly."

Oliver, 38, joined the Balch Springs department in 2011 but was fired after the fatal shooting, which was thrust into a national conversation about police killings of African Americans.

The trial is expected to last about two weeks and highlights the heightened role video evidence plays in high-profile police shootings that have stirred discourse and protests nationwide over issues of race and law enforcement.

Its importance was on display Thursday as jurors saw footage captured by body cameras worn by Oliver and Gross the night of the shooting. Footage shows the two officers breaking up a house party, with high-school age kids streaming away from the residence and attempting to avoid mud outside.

Police were having a friendly conversation with the party's host when gunfire, later found to be fired near a nursing home, cut the exchange short.

Footage shows people screaming outside. Video shows Oliver getting a rifle from his patrol car and going toward Gross, who was trying to get the vehicle to stop.

Police footage played for jurors shows the car slowly backing up before driving forward. After firing on the car containing Edwards and the other teens, Oliver can be heard asking Gross if he's all right. Oliver then says the driver of the vehicle tried to hit Gross.

Gross testified Thursday that he didn't feel like the vehicle was trying to hit him.

Following the shooting, the Balch Springs police chief reported that police video had contradicted his agency's original statement on the incident. Police first said the vehicle backed up toward officers "in an aggressive manner," but police later said video showed the vehicle was moving forward as officers approached.

Gross estimates there were dozens of kids coming out of the residence. Gross testified he saw no drunk teens and only saw one beer bottle. He also said there were no indications of violence.

Vidal Allen testified Thursday that Edwards, his step brother, gave him the idea to go to the party and they received permission before attending.

At the party, he said, there was dancing, rap music and a crowd having a good time. Police arrived and Allen said he dashed from the party through the backyard and went to the car.

With the five teenagers in the vehicle, Allen said he tried to leave the party by going straight down the road, but police were blocking the road.

Instead, he backed up slowly and heard somebody yelling at them to stop the car, he said. But he testified he did not know who was yelling and didn't know it was a police officer giving the commands.

"I just wanted to get home," he said, because the teenagers had heard the gunfire that rang out near the nursing home.

The police shooting, he said, all seemed to happen in an instant. Allen testified he steered the vehicle clear of officers while leaving.

Some legal experts said ahead of the trial that securing a conviction against an officer is a challenge because criminal culpability in such cases is subjective and jurors are more inclined to believe police testimony.

Philip Stinson, a criminologist at Bowling Green State University in Ohio who tracks police shootings, said jurors are often reluctant to second-guess the decisions of an officer faced with an intense street encounter. Even when armed with video evidence, attorneys can fail to deliver a conviction against an officer, he said.

Edwards' stepmother, Charmaine Edwards, testified that her stepson played football from age 6 and was "really into his academics." She testified that he got A's and B's in school and was a people person, close to his brothers.

Oliver has a history of hostile and aggressive behavior and "flipped off" the vehicle that held Edwards' body following the shooting, according to court filings from prosecutors. Oliver, while in the eighth grade, posted swastikas in public places, hated anyone who was not Caucasian and was also a member of the group "Caucasians in Effect," the court filing says.

In 2013, he was "uncooperative and used profanity" while testifying in trial, according to the records, and "communicated aggressively" and used profanity with prosecutors that same day.

Oliver's legal troubles extend beyond the murder trial. A lawsuit has been filed over the shooting, and Oliver has been indicted in a separate 2017 incident in which police said he drew a weapon after he was rear-ended while off duty.