A former Dallas police officer who killed her neighbor after she walked into his apartment has been found guilty of murder.

Amber Guyger, an officer at the time of the shooting, had claimed that she had thought she was in her own apartment, and the man was an intruder.

Tuesday's conviction of Guyger elicited cheers from the hallway outside the courtroom and sobs from family of her unarmed black victim, The Dallas Morning News reported. Attorneys for the man's family cast it as a historic moment that would resonate across the country.

"This is a huge victory not only for the family of Botham Jean but, as his mother told me a moment ago, this is a victory for black people in America," attorney Lee Merritt told reporters. "It's a signal that the tide is going to change here; police officers are going to be held accountable for their actions."

Jury deliberations resume Tuesday afternoon to determine Guyger's sentencing. She could get 5 to 99 years, or life in prison; parole is not an option, the Morning News reported.

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The verdict followed a high-profile seven-day trial that reconstructed the evening of Sept. 6, 2018, when Guyger said she mistakenly entered Jean's apartment. The off-duty officer said she thought she was in her unit, one floor below, and that the unarmed accountant was burglarizing her home.

But Guyger, a white woman who had just finished a long shift at work, was on the wrong floor of the building. In a matter of seconds, prosecutors said, Jean - who was watching TV and eating ice cream in his own apartment - was dying on the ground, a fatal gunshot wound in his chest. He was 26 years old.

The shooting touched off days of protests in Dallas and demands for police reform. Many saw it as another egregious example of a white officer killing an unarmed black man, part of a pattern of police wielding deadly force disproportionately against people of color.

But the unusual facts of this case made it unique among other high-profile fatal police shootings, most of which are never even prosecuted.

During the trial, Guyger took the stand, offering a tearful defense and repeated apologies.

"I shot an innocent man," she said during her testimony, the first time the public had heard from her since the shooting.

Guyger's lawyers have said the 31-year-old, who was fired from the police force shortly after she killed Jean, was exhausted and scared when she heard someone inside the unit she thought was her own that night. She opened the door, saw a "silhouette figure" in the dark apartment and feared for her life, they said. She said she asked to see his hands, but he just walked toward her. She fired two shots.

By her own admission, she was shooting to kill.

But because she believed she was in her own home, her legal team argued, she was within her rights, acting in self-defense. It was "a series of horrible mistakes," the lawyers said - "awful and tragic, but innocent."

Dallas County District Court Judge Tammy Kemp ruled Monday that the jury could consider the "castle doctrine," a controversial law that says your home is your castle and you have a right to defend it. Kemp's decision "raised the bar for prosecutors and sparked outrage and disbelief from critics who questioned how the law could protect Guyger when she shot Jean in his own apartment,"according to a previous Washington Post report.

On Tuesday, lawyers for the Jean family joined the chorus of critics, saying it was "asinine" for the doctrine to go before the jury. Attorney Benjamin Crump compared it to the controversial stand-your-ground law, describing both as attempts to "come up with justification to kill an unarmed black person."

The prosecution cast Guyger as careless and negligent - armed, distracted and too quick to pull the trigger. The state's lawyers called her defense "garbage" and "absurd."

They said a reasonable person would have noticed the illuminated apartment numbers that read 1478, rather than 1378, and would have seen Jean's red doormat. She wasn't paying attention, prosecutors said, because she was too caught up in a sexually explicit conversation she was having with her partner on the police force.

"I mean, my God," said Jason Fine, the Dallas County Assistant District Attorney. "This is crazy."

Prosecutors also questioned why Guyger even opened the door when she suspected someone was inside, arguing that police training teaches officers confronting a burglar to take cover and call for backup.

"For Amber Guyger, Mr. Jean was dead before that door ever opened," said Jason Hermus, the lead prosecutor.

Jurors had to decide whether Guyger was guilty or not guilty of murder or manslaughter.

Shortly after they began deliberating on Monday, Merritt told reporters that the ruling would have far-reaching consequences.

"The jury is out," he said, "and what they take back to that jury room, in our opinion, is the decision of the value of black life."

After the verdict was announced, the attorneys said they had expected a conviction, pointing to the fact that Jean was unarmed, completely non aggressive and in his own apartment. He was also, Crump said, "a near-perfect person of color": a college-educated accountant working for PricewaterhouseCoopers, one of the top three firms in the world.

Listing off the names of other unarmed black people killed by police, from Tamir Rice to Eric Gardner, the attorney said the jury's decision sets a precedent that will help spur equal justice under the law.

"For so many unarmed black and brown human beings all across America," he said, "this verdict today is for them."