A Dallas jury has unanimously found former police Officer Amber Guyger guilty of murder for fatally shooting her neighbor who lived in the apartment above hers. She had testified that she entered Botham Jean's unit, thinking it was her own home after a long day at work, and thinking he was an intruder.

She faces a possible penalty of up to 99 years in prison.

Prosecutors maintained that Guyger committed murder when she overlooked indications that the apartment was not her own — the wrong floor, the smell of marijuana coming from the apartment, a bright red doormat — and shot Jean, a 26-year-old accountant who was sitting in his living room eating ice cream when Guyger killed him last September.

"There was no other floor mat like this is the entire building. This sticks out, literally, like a red thumb," lead prosecutor Jason Hermus said in court on Monday, holding up the doormat to the jury. "And she walked up to it and stood on top of it."

But in tearful testimony to the jury, Guyger said she was "scared to death" when she opened what she thought was her own apartment door and saw the silhouette of a man she mistook him for an intruder.

"I was scared whoever was inside my apartment was going to kill me," she told the jury. "No police officer would want to hurt an innocent person."

Guyger lived on the third floor of an apartment complex just south of downtown Dallas. Her lawyers have said that she was winding down a 13-hour work day when she opened Jean's door.

"What was going through Amber's mind was just, 'I'm going home,' " defense lawyer Robert Rogers said. " 'I'm exhausted, and I'm going home.' "

Guyger said she put her key in the door and realized it was unlocked. Thinking someone had broken in, she drew her gun and entered the apartment.

Then Guyger said she told Jean, "Let me see your hands," and that he instead started to move toward her. Prosecutors counter that nobody in her apartment complex heard her instruct Jean to raise his hands.

Within seconds of opening the door, she fired two shots at Jean. One of the bullets struck him in the chest, killing him.

Guyger then called 911 and told the operator over and over: "I thought it was my apartment."

The case became transfixing to observers around the country for the delicate questions it presented. Was the shooting a noncriminal accident equal to a "tragic mistake," as Guyger's lawyers argued? Or were the mistakes of Guyger so reckless that they constituted manslaughter, or so intentionally negligent that it amounted to murder?

In deciding that she was guilty, the jury, about half of whom were African American, sided with the prosecution, meaning Guyger now faces decades of possible prison time.

Others have described the facts of the case as the latest example of a white police officer killing an unarmed black man. Civil rights groups rallied behind Jean, a native of the Caribbean island of St. Lucia. And police officers came to the defense of Guyger.

Guyger attempted to cast aside race as being a factor by saying during her testimony that the encounter was "not about hate," she said. "It's about being scared."

To prosecutors, Guyger's distraction led to a crime.

Just before she entered Jean's apartment, Guyger had a 16-minute conversation with a fellow officer, Martin Rivera, whom authorities say was a romantic partner of Guyger's and the two had been swapping sexually explicit messages.

Prosecutors argued that Guyger was so absorbed with those communications that she was too preoccupied to realize she was heading toward the wrong apartment.

Prosecutors, in cross-examining Guyger, emphasized that her training as a police officer should have informed her to back away from the door, hide and call for backup.

Guyger had her police radio on her, and she lives just two blocks away from police headquarters, so she could have had other officers arrive quickly, prosecutors pointed out. Had she done that, Guyger was asked, might Jean be alive today?

"Yes, sir," she said.

In the state's closing arguments on Monday, prosecutor Hermus said the only way a defendant can claim self-defense to murder is when there is no other reasonable alternatives.

Hermus said that was not the case when Guyger shot Jean.

"Self-defense means you're acting defensively," Hermus said. "She became the aggressor. That's not self-defense."

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