Fort Worth Interim Police Chief Ed Kraus vowed a white former police officer would be held accountable for killing a 28-year-old black woman inside her home over the weekend. Aaron Dean, who resigned Monday before he could be fired from the police department, was out on bond after being arrested and charged with murder in the death of Atatiana Jefferson.

Police said officers went to Jefferson’s home early Saturday morning for a wellness check after her neighbor called the department’s non-emergency number, saying the front door of the home had been left open. The department said an officer perceived a threat while outside the home and fired a shot, striking Jefferson inside through a window. Body camera video shows Dean fired less than a second after yelling for Jefferson to show her hands and that he never identified himself as a police officer.

Family attorney Lee Merritt said Jefferson had been up late playing video games with her 8-year-old nephew, leaving the door open to let in the fall breeze, when they heard a sound outside. Merritt said the child told him his aunt wouldn’t let him go to the window to investigate, instead going herself.

According to a newly released arrest affidavit, Jefferson grabbed her handgun as she went toward the window. The boy said she had the handgun raised and pointed toward the window when she was shot.

Speaking during a news conference Tuesday, Kraus again apologized for Jefferson’s death.

“There’s absolutely no excuse for this incident, and the person responsible will be held accountable,” Kraus said.

Merritt said Jefferson legally owned the gun and was licensed to carry. Speaking generally before the child’s account was publicly available, Kraus said on Monday that it would make sense for Jefferson to pick up a gun if she thought someone was prowling in her yard, acting as many homeowners in Texas might. Kraus said he regrets circulating an image of the gun found inside the home, which Merritt said was an attempt to blame the victim.

Jefferson’s family is relieved Dean was arrested but said more needs to be done to change the police department, CBS News correspondent Omar Villafranca reported Tuesday. Kraus vowed that the department would work to “serve you better.” He said the department was aiming to bring in a third-party group to evaluate policies, practices and training “to ensure we are above best practice standards.”

On Tuesday, Kraus said he couldn’t explain what Dean perceived when he opened fire because the officer has not spoken with investigators. When asked why officers didn’t announce themselves or knock on the door, Kraus said the officers were responding to an “open structure” call and might have responded differently if they thought the home was being burglarized.

Kraus urged the community not to judge the rest of the department by the actions of one officer. When asked about morale within the police department, he said officers had praised him for acting swiftly to condemn Dean’s actions.

Kraus grew emotional when he spoke about how the shooting would affect the relationship between the police department and the community, tearing up and cutting the press conference short.

“It’s very emotional because the officers, they try hard every day to make this city better,” Kraus said. “…Some of our officers that are out there every weekend and most weeknights, out there trying to build these relationships, I likened it to a bunch of ants building an anthill, and then someone comes with a hose and washes it away and they just have to start from scratch and build over. I think that’s gonna be all, thank you,” he said, abruptly leaving the podium.

On Twitter, Merritt called for justice for Jefferson and changes at the police department.

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

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