(CNN) A concerned neighbor called police at 2:23 a.m. to check on the woman across the street because her front door was open. At 2:30 a.m., she would be dead.

Aaron Dean, a white police officer, shot and killed Atatiana Koquice Jefferson , a 28-year-old black woman, through her window early Saturday morning in Fort Worth, Texas. Police say Dean did not identify himself as an officer before shooting.

He was arrested on a murder charge Monday night, police said.

Activists and family members are calling for an independent investigation.

Here's what we know about the shooting:

It began with a request to check on a neighbor

Atatiana Jefferson

James Smith, Jefferson's neighbor, told the Fort Worth Star-Telegram he called a non-emergency police number when he saw that her doors had been open for an extended period of time in the early morning hours. He said he knew Jefferson was home with her nephew, and was worried about them.

"I'm shaken. I'm mad. I'm upset. And I feel it's partly my fault," he told the newspaper. "If I had never dialed the police department, she'd still be alive."

Smith placed the call at 2:23 a.m., and officers responded to Jefferson's home at 2:28 a.m., according to a police incident report.

Police went around the outside of the home

Officers arrived and parked near but not in front of the residence, police spokesman Lt. Brandon O'Neil said Sunday at a news conference.

Jefferson was at home playing video games with her 8-year-old nephew when police arrived, said Lee Merritt, a civil rights lawyer representing Jefferson's family.

A heavily edited body camera video released by police shows the lights of the house were on when officers first arrived. A front door and a side door were open, with the accompanying glass storm doors closed. No one can be seen inside.

The officers can be seen walking around the home in the dark, holding a flashlight. At some point, one of them quickly approaches a window with his weapon drawn.

Body cam footage released by the Fort Worth Police department. This image is part of heavily edited video released by police on Saturday.

An officer shot through the window after 'perceiving a threat'

Within seconds, the officer yells, "Put your hands up! Show me your hands!" and fires through the window.

Police said that the officer drew his weapon and fired one shot after "perceiving a threat."

Jefferson's 8-year-old nephew was in the room with Jefferson when the shooting happened, O'Neil said.

The officers entered and rendered medical aid to Jefferson, but she died at the scene, police said in a statement.

The medical examiner said Jefferson died at 2:30 a.m. Saturday morning, in the bedroom of her home.

A still frame of body cam footage released by the Fort Worth Police department showing a weapon found at the scene. This image is part of heavily edited video released by police on Saturday.

The child would later tell an investigator that Jefferson, after hearing noises outside, had taken out a handgun from her purse and pointed the gun toward the window, police said

The officers found a firearm when they entered the room, police said. Video released by police shows two mostly blurred clips that appeared to be from inside the home, showing a firearm.

"It makes sense that she would have a gun if she felt that she was being threatened, or if there was someone in the backyard," Fort Worth interim Police Chief Ed Kraus told reporters on Tuesday.

The officer who shot Jefferson was charged with murder

Dean posted bail Monday night, three hours after being arrested. He had been held in the Tarrant County Jail with bond set at $200,000.

#UPDATE

Aaron Dean was arrested by Fort Worth Police

on Oct. 14. Dean has been charged with

murder of Atatiana Jefferson. Dean is in

the Tarrant County Jail.



Interim @chiefkraus will schedule a News

Conference for Oct. 15 at Bob Bolen. That time has not been determined yet. pic.twitter.com/eRZfMWtgM4 — Fort Worth Police (@fortworthpd) October 15, 2019

The Jefferson family "is relieved" that Dean was arrested, Merritt wrote on Twitter.

"We need to see this through to a vigorous prosecution & appropriate sentencing. The City of Fort Worth has much work to do to reform a brutal culture of policing," Merritt said.

The officer resigned from the department Monday morning, Kraus said. Dean was hired in August 2017 and commissioned as a licensed officer in April 2018.

Dean was served with a written administrative complaint Sunday, placed on detached duty and stripped of his badge and gun, Kraus said.

"My intent was to meet with him today to terminate his employment with the Fort Worth Police Department. However, the officer tendered his resignation this morning before we met," Kraus said.

If Dean had not resigned, he would have been fired for several policy violations, including the department's use of force and de-escalation policies, and unprofessional conduct, Kraus said.

As of Monday, Dean had refused to speak with detectives about what happened, an affidavit accompanying his arrest warrant said.

Dean's attorney, Jim Lane, told CNN Tuesday that the former officer is remorseful.

"My client is sorry and his family is in shock, Lane said.

Police are investigating

The Fort Worth Police Officer's Association said in a statement it is "deeply saddened" by the shooting.

"Any loss of life is tragic, but the reported circumstances surrounding this incident are heartbreaking," the statement said. "We are urging the Fort Worth Police Department to conduct a thorough and transparent investigation, and through that investigation we hope to gain clarity and understanding of what transpired."

Saturday's shooting is the ninth in 2019 by Fort Worth police, seven of which were fatal, police said.

Fort Worth police presented a preliminary case to the FBI to review Dean's actions for possible civil rights violations, according to Kraus.

But police had yet to formally present the case to the Tarrant County criminal district attorney's office, officials said Tuesday.

There are calls for an independent investigation

Neighbors and activists told KTVT they're calling for an independent federal investigation and that they want Kraus to step down.

"We don't think that Fort Worth police should be investigating it on their own," Merritt told CNN Sunday. He said police reached out to his clients, but they'd rather talk with independent investigators about the shooting.

Flowers are laid out in front of the home where 28-year-old Atatiana Koquice Jefferson was shot and killed by a police officer.

Merritt also represented the family of Botham Jean, a black man who was fatally shot in his home by a Dallas police officer when she walked into the wrong apartment. Merritt said Jefferson's family was following that trial, like much of the Dallas-Fort Worth area, and they reached out to him Saturday afternoon.

"It's another one of those situations where the people that are supposed to protect us are actually not here to protect us," Jefferson's sister, Amber Carr, told KTVT . "You know, you want to see justice, but justice don't bring my sister back."

"The death of Black citizens by white officers has reached critical mass," the National Black Police Association said in a statement. It called for "all law enforcement agencies to be responsible in hiring and training" so that a situation like this doesn't happen again.

The Lawyers' Committee for Civil Rights Under Law, a nonprofit organization, called for the US Justice Department to investigate the Fort Worth police.

"In the weeks and months ahead, many African Americans across our country may harbor fear about the unintended and fatal consequences that can result from simply calling 911 for help," said Kristen Clarke, president and executive director of the Lawyers' Committee for Civil Rights Under Law.

Jefferson was a pre-med graduate

Jefferson, known by family as "Tay," was a pre-med graduate of the historically black Xavier University of Louisiana who was very close to her family, according to a verified GoFundMe page raising money for her family.

The Xavier community was "deeply dismayed" by the news of Jefferson's death, University President Reynold Verret said in a statement Sunday.

Merritt said she graduated with a biology degree in 2014 and went on to work in pharmaceutical equipment sales. Jefferson moved into her sick mother's home to take care of her at the beginning of the summer, Merritt said.

Jefferson has a brother and two sisters, the lawyer said. Merritt described her as the type of person who would play video games with her 8-year-old nephew until 2 a.m., which is what she was doing at the time of the shooting.

The 8-year-old was the first to tell his mother, Jefferson's sister, about the shooting, family members said during a news conference Monday.

"We've noticed things about him that changed, but he's a strong one," said Adarius Carr, Jefferson's brother. "We'll get him the treatment he needs to make sure he's good."

Carr added the case has been "a whirlwind."

"Slowly but surely, we are allowing ourselves to feel," he said. "It's been a lot."