FORT WORTH, Texas — A white Fort Worth police officer who shot and killed a black woman in her home while responding to a call about an open front door acted without justification and resigned Monday before he could be fired, the police chief said.

Police bodycam video showed that Aaron Dean did not identify himself as an officer and fired a split-second after shouting at Atatiana Jefferson to show her hands. Jefferson, 28, was killed in front of her 8-year-old nephew, cut down by a bullet fired through her window early Saturday.

“Nobody looked at this video and said that there’s any doubt that this officer acted inappropriately,” Interim Police Chief Ed Kraus said.

Kraus said Dean would have been fired if he had not quit. He said that a criminal investigation is underway and that he expects an update by Tuesday on whether the 34-year-old former officer — a member of the force for 1½ years — will be charged.

Earlier in the day, Jefferson’s family had demanded that Dean be fired and arrested.

“Why this man is not in handcuffs is a source of continued agitation for this family and for this community,” family attorney Lee Merritt said.

Police went to Jefferson’s home about 2:25 a.m. after a neighbor called a non-emergency line to report that her door had been left open. In a statement over the weekend, the department said officers saw someone near a window inside the home and that one of them drew his gun and fired after “perceiving a threat.”

The body camera video released by police showed Dean shouting, “Put your hands up! Show me your hands!” and immediately firing.

Jefferson was staying up late, playing video games with her nephew, when she was killed, according to the family’s attorney.

As for what, exactly, led Dean to open fire, the police chief said: “I cannot make sense of why she had to lose her life.”

The video included images of a gun inside a bedroom. The police chief said that he did not know whether Jefferson was holding the weapon when the officers approached in the backyard but that the gun was found near the window.

Kraus said that, in hindsight, releasing the images of the weapon was “a bad thing to do,” noting that many Texas homeowners keep guns nearby for self-defense.

“We’re homeowners in Texas,” he said. “Most of us, if we thought we had somebody outside our house that shouldn’t be and we had access to a firearm, we would be acting very similarly to how she was acting.”

Texas has had a “castle doctrine” law on the books since 2007 that gives people a stronger legal defense to use deadly force in their homes. The law was backed at the time by the National Rifle Association and is similar to “stand your ground” measures across the U.S. that say a person has no duty to retreat from an intruder.

Fort Worth is about 30 miles (50 kilometers) west of Dallas, where another high-profile police shooting occurred last year.

In that case, white Dallas police officer Amber Guyger shot and killed her black neighbor Botham Jean inside his own apartment after Guyger said she mistook his place for her own. Guyger, 31, was sentenced this month to 10 years in prison.

A large crowd gathered outside Jefferson’s home Sunday night for a vigil after earlier demonstrations briefly stopped traffic on Interstate 35. A single bullet hole was visible in the window of the single-story, freshly painted purple home, and floral tributes and stuffed animals piled up in the street.

The police chief said Dean could face state criminal charge and that he has also submitted a case to the FBI to review for possible federal civil rights charges.

Dean has not yet hired an attorney but will have one provided with financial support from the state’s largest police union, the Combined Law Enforcement Associations of Texas, according to Charley Wilkison, executive director.

Relations with the public have been strained after other recent Fort Worth police shootings. In June, the department released footage of officers killing a man who ignored repeated orders to drop his handgun. He was the fourth person Fort Worth police had fired upon in 10 days.

Nearly two-thirds of the department’s 1,100 officers are white, just over 20% are Hispanic, and about 10% are black. The city of nearly 900,000 people is about 40% white, 35% Hispanic and 19% black.

Kraus took over as interim police chief in May after the previous chief was fired.

Jefferson was a 2014 graduate of Xavier University in New Orleans and earned a bachelor’s degree in biology. She was working in pharmaceutical equipment sales and was considering going back to medical school, according to the family’s lawyer.

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