Updated at 6:18 p.m. Revised to include details from neighbors' testimony.

Officers scrambled up stairs and down hallways, breathing hard as they rushed toward Botham Jean, who lay dying last September on the floor of his Dallas apartment. First responders desperately took turns performing CPR as Jean lay unconscious with only a faint pulse.

On Tuesday, jurors in Amber Guyger's murder trial watched body-camera footage from Sept. 6, 2018, the night that Guyger, an off-duty Dallas police officer, fatally shot Jean in his apartment.

Jury watching body camera video from officer who responded to scene when Amber Guyger shot and killed Botham Jean. Not showing the graphic scene. Officers give CPR. Guyger in apartment when they arrive. ➡️ https://t.co/050hOCLe8R pic.twitter.com/VbuBSV7SqI — Larry Collins (@LarryNBC5) September 24, 2019

Guyger, 31, has said she mistook Jean's apartment for her own that night and shot the 26-year-old thinking he was a burglar.

Her attorneys have argued that she "firmly and reasonably" acted in fear for her own life when she shot her upstairs neighbor, while prosecutors questioned how she missed several visual cues that indicated she was in the wrong apartment.

Guyger, who was later fired, looks panicked when she appears briefly in Officer Michael Lee’s body-cam footage.

Read more: First day of Amber Guyger's murder trial focuses on sexual texts with police partner

“I thought it was my apartment. I thought it was my apartment,” she repeats as Lee moves past her, putting on a pair of blue gloves. He orders her to move away from Jean.

“Chief, hey, can you hear me?” one officer says to Jean, who was on the floor in light-colored shorts and a dark T-shirt. “Can you hear me?”

A panicked Dallas police officer Amber Guyger (left) is pictured on police body-cam footage as other Dallas police officers arrive in Botham Jean's apartment. The video was played for the jury in her murder trial Tuesday. (Tom Fox / Staff Photographer)

Lee testified that despite officers’ efforts, Jean didn’t open his eyes or otherwise communicate with first responders.

The lights in the apartment were on by the time first responders arrived, and Lee testified that Jean’s TV and laptop also were on. The footage shows a bowl of vanilla ice cream on his ottoman and an ironing board and iron set up nearby.

Ear buds lay on the floor near Jean and prosecutor Jason Hermus, a former police officer himself, suggested that he could have been wearing them when Guyger arrived.

Jean's family, including his brother and sister, left the courtroom before that video was played. But Jean's teenage brother, Brandt, returned by the time it was shown again. He sat with his chin in his hand as the courtroom watched officers frantically try to save his brother's life.

Hermus showed jurors a photo of the uniformed officer standing in the hallway on her cellphone, as other officers worked inside to save Jean.

The prosecutor asked Lee, the officer whose body-cam footage recorded Jean undergoing CPR, about a hypothetical break-in where an officer comes upon a burglary in progress and notices someone inside a residence.

"You have two choices," Hermus said. "I want you to presume that you can safely ... reposition to a position of cover and concealment. You have that option. Or you can just shoot them dead and worry about that later. What do you do?"

"Cover and concealment," Lee answered.

"Is that because of the sanctity of human life?" Hermus asked him.

"Yes, sir," Lee said.

Dallas police officer Michael Lee listens and watches footage from his body camera during testimony in Amber Guyger's murder trial. Lee was one of the first responding officers to the scene and performed CPR on Botham Jean. (Tom Fox / Staff Photographer)

Lee, in response to questions from Guyger's defense, said he was in the same police academy class as Guyger. He said she seemed "very emotional" the night of the shooting.

Robert Rogers, one of Guyger's attorneys, asked Lee whether it was important to be able to see a suspect's hands to determine whether that person was a threat, and whether he would be prepared to use deadly force to protect himself if he walked into his home and believed an intruder was there.

Lee testified that he would.

Jurors later saw a video walk-through of the crime scene from Sept. 8, 2018, filmed by a Texas Ranger while Ranger David Armstrong was on the stand.

In the kitchen, they saw Jean's counter with syrup, soap and a bag of tortilla chips sitting out, and dishes in the sink. In the living room, there was the ordinary: Jean's bowl of melted vanilla ice cream and a copy of rapper Gucci Mane's autobiography on the ottoman, a blanket on the floor near the couch. His degree from Harding University in Arkansas was on display.

But there were also signs that were far from mundane: a blue medical glove left behind, blood on the floor and a bullet hole in the back wall.

On the counter also sat a bag of cookies, which he had crumbled into his ice cream. It had still been frozen when first responders arrived.

Texas Rangers investigator video from inside Botham Jean’s apartment 2 days after his death shown to jury. ➡️ https://t.co/050hOCLe8R pic.twitter.com/a9i1a062dy — Larry Collins (@LarryNBC5) September 24, 2019

Three men who lived on the fourth floor of South Side Flats near the apartment where Jean was killed took the stand Tuesday afternoon.

One was Joshua Brown, who lived across the hall from Jean. He had been coming home the night of Sept. 6, 2018, when he heard what he thought sounded like "two people meeting by surprise."

He testified that he couldn't make out what they were saying and they were speaking at the same time. The prosecution asked if Brown had heard loud commands like "Hey, put your hands up!" or "Show me your hands!"

He said he had not. The two other neighbors who took the stand said the same.

Brown testified that he just met Jean for the first time the day he was killed. They had just a brief conversation in the hallway.

But, Brown said, he did hear him from time to time.

"I heard him singing," Brown said. Gospel music. Drake.

Jean's family smiled and nodded. Jean loved to sing and was a song leader in his church.

On the witness stand, Brown began to cry and bowed his head. The judge passed him a box of tissues.

He was so upset, Kemp sent the jury out of the room and called a recess. Brown had calmed down by the time he got back on the stand.

Read more: Who is Tammy Kemp, the judge presiding over Amber Guyger's murder trial?

Earlier Tuesday morning, jurors heard the 911 call that Guyger made after the shooting.

She repeatedly told the operator that she had made a mistake. Jean's father, Bertrum Jean, put his arm around his wife, Allison, as the audio played in the courtroom.

Guyger wiped away tears and dropped her head as her words from the 911 call filled the courtroom.

"I'm an off-duty officer," Guyger said in the recording. "I thought I was in my apartment, and I shot a guy thinking it was my apartment."

Also during Tuesday's testimony, a police detective said Guyger had no drugs or alcohol in her system at the time of the shooting. The results of her blood draw had not been publicly released until then.

Audio from the 911 call was previously obtained by WFAA-TV (Channel 8), but Tuesday was the first time it was officially released. Four of the 12 jurors had never heard the 911 call before, prosecutors said in a hearing before the trial began.

"I thought it was my apartment," Guyger repeated, breathing heavily in the audio. "I could've sworn I parked on the third floor."

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