CNN  — 

In her final months, Atatiana Jefferson moved to another city to take care of her ailing mother.

In her final minutes, the 28-year-old tried to protect her nephew from what they both thought was a prowler.

But in her final seconds, a Fort Worth police officer shot into Jefferson’s bedroom, killing the beloved aunt “Tay” in front of the 8-year-old boy.

Atatiana Jefferson was killed after playing video games with her nephew.

“He saw her when she fell,” said Lee Merritt, an attorney for Jefferson’s family. “He was present the entire time. He never left the room.”

As Texans mourn the death of another black person killed at home by a white officer, the 8-year-old who witnessed the killing had to break the news to his mother.

A deeply devoted aunt and daughter

Jefferson moved into her ailing mother’s Fort Worth home a few months ago to take care of her, Merritt said.

She also took great care of her nephews, especially when her older sister Amber was recently hospitalized.

“She came to the hospital in Plano where I was recovering from a major heart surgery,” Amber Carr said. “She came and brought me food. She brought me a new cell phone.”

Jefferson was looking forward to taking her nephews to the State Fair of Texas while her sister recovered.

“The relationship she has with my sons is indescribable,” Carr said. “Sometimes people think that they’re her kids, not mine.”

The beloved aunt died protecting her nephew

Friday night, Jefferson stayed up late to play video games with her nephew. They played Call of Duty into the wee hours of Saturday morning, a mental reprieve as the boy’s grandmother – Jefferson’s mother – was in the hospital.

After weeks of searing weather, they decided to enjoy the crisp autumn air.

“They opened the doors, allowed the breeze to flow through the house,” Merritt said.

Around 2:25 a.m., a concerned neighbor noticed the doors to the house were open. He called a non-emergency police number to ask for a safety check at Jefferson’s house.

Body camera footage shows an officer peering through two open doors, but he doesn’t knock or announce his presence. Instead, he keeps walking around the perimeter of the house, including through a closed gate.

Inside the house, the boy was terrified, Merritt said.

“He and his Auntie Tay experienced the fear of someone prowling in the backyard,” Merritt said.

“His Auntie Tay did not allow him to check the windows. She checked herself.”

Eventually, the officer approaches a window, shining a flashlight into what appears to be a dark room.

“Put your hands up! Show me your hands!” the officer screams. He does not identify himself as police.

Within two seconds of starting his verbal commands, the officer fires a shot through the window while he’s in the middle of saying “show me” for the second time.

Jefferson was pronounced dead minutes later.

Fort Worth police said the officer fired his gun after “perceiving a threat.”

Merritt said Jefferson had a legally owned gun and a license to carry. He said the aunt had every right to have the gun with her when she and her nephew thought someone was lurking near the home.

“Firearms are used to protect individuals from predators prowling about their property. That’s only common sense,” Merritt said. “(Police) created a deadly situation.”

The 8-year-old broke the news to his mom

Carr, who had been recovering from heart surgery, said she didn’t know her sister had died until she talked to her son.

“The first thing he told me was he was sad. And I asked him why was he sad. And he told me because the police had shot his aunt,” Carr said.

“At that time, I knew nothing about that. So he was the one who actually told me what had happened.”

Atatiana Jefferson was very close to her family, including her nephew and three siblings.

The boy shared a special bond with his “Aunt Tay.” They didn’t just play video games together – Aunt Tay also taught him life skills, such as writing a schedule to help him stay organized and teaching him to be better prepared for school.

Carr said she’s amazed her young son is staying strong despite witnessing such horror. Now he’s helping his mother cope.

“In the middle of the night when I’m crying, he wakes up and tells me to breathe in my nose and out my mouth,” Carr said.

“He holds me. He hugs me. And these are the things I should be doing for him, but … he’s helping me to be strong. And I believe that’s because my sister had a big part in that.”

Adarius Carr, Jefferson’s brother, told CNN his nephew was a “very smart child” who was wise beyond his years, but was still affected by the shooting.

“We’ve noticed things about him that changed, but he’s a strong one,” Adarius Carr said. “We’ll get him the treatment he needs to make sure he’s good … He’s doing strong, we believe in him.”

Jefferson was a bookworm who loved to learn

Marquis Jefferson told CNN affiliate KTVT that he takes solace in fond memories of his daughter while he’s grappling with her death.

“When she was growing up, I read to her a lot. I bought her a lot of books,” the father told KTVT. “Oh, she loved to read all the time. Her mother would tell me, ‘She’s in there reading, reading, reading.’ “

Mourners left flowers in front of the house where 28-year-old Atatiana Jefferson was killed.

Jefferson’s love for learning led to her pre-med degree in biology from Xavier University of Louisiana. After graduating in 2014, she started working in pharmaceutical equipment sales, Merritt said.

Xavier President Reynold Verret said he was devastated by the news.

“We are deeply dismayed by the news of another African American killed in her own home by the police,” wrote the president of the historically black university.

Just 30 miles east of where Jefferson was shot, Botham Jean was killed in his apartment last year by a Dallas police officer who mistook his apartment for her own.

“We should expect safety when we call on our police, whose mission is to protect and serve,” Verret wrote.

“Families in our communities hesitate to call on their protectors out of fear that they be killed. … Trust must be established to repair a system that does not serve all equally.”

A family devoted to service demands justice

Adarius Carr, who’s stationed in San Diego with the US Navy, rushed to Texas after learning his sister was killed.

He said he’s bewildered by the police officer’s actions the night his sister died.

“This man murdered someone. He should be arrested,” Adarius Carr said, breaking down in tears.

As a 12-year member of the military, “I’ve been trained and taught there are preplanned responses to everything you do,” he said. “And when you don’t do it the way you’ve been trained, or the way you’ve been taught, you have to answer to that. … You know better.”

Jefferson’s family said police took the life of a woman committed to helping others.

“Service is real big for our family,” Adarius Carr said. “We want to give back to this world. We want to make it a better place.”

Merritt said Jefferson’s final act of service may have saved her nephew’s life.

“His Auntie Tay did not allow him to check the windows. She checked herself,” Merritt said. “What would have happened if that little boy went to the window instead of his auntie?”

CNN’s Dave Alsup and Amir Vera contributed to this report.