The Fort Worth police officer who shot and killed Atatiana Jefferson has been arrested and charged with murder, the department announced Monday.

Aaron Dean shot and killed Jefferson, who was black, in her mother’s home Saturday. He resigned Monday, according to the Fort Worth police department.

Body camera footage released over the weekend showed an officer surveying the area around the house after seeing an open front door. The officer opened the backyard gate, noticed movement in the window and shouted, “Put your hands up, show me your hands.” The officer then fired through the window, killing Jefferson, police said. Jefferson’s 8-year-old nephew was in the room at the time, police said.

At a press conference, Fort Worth Police Chief Ed Kraus identified Aaron Dean as the officer who shot Jefferson. Kraus also apologized to Jefferson’s family and the Fort Worth community, and said he had planned to terminate Dean’s employment prior to his resignation.

“Her father called this shooting ‘senseless’ and I certainly cannot make sense of why she had to lose her life,” Kraus said. “On behalf of the Fort Worth Police Department, I am so sorry for what occurred.”

“Even though he no longer works for the city, we will continue the administrative investigation as though he did,” Kraus later said. “Had the officer not resigned, I would have fired him for violations of several policies including our use of force policy, our de-escalation policy, and unprofessional conduct.”

Officials said the officer did not announce himself as law enforcement prior to giving orders or shooting the woman. They have said the approach will be addressed in their investigation. Additionally, Kraus said Dean has been uncooperative with the investigation and the officer who accompanied Dean is being treated as a witness.

“None of this information can ease the pain of Atatiana’s family, but I hope it shows the community that we take these incidents seriously,” Kraus said.

Kraus said he expects a “substantial update” on the internal investigation Tuesday. Kraus said the Texas Rangers declined to investigate the shooting and that the case has been submitted to the FBI for potential civil rights violations. Prior to the chief’s statement, Fort Worth Mayor Betsy Price announced a plan for a third-party review of the police department’s policies and procedures.

Police responded to the home after James Smith, Jefferson’s neighbor, requested a wellness check. However, Kraus said the officers responded to what he described as an open structure call, which is different from the procedure for a wellness check. According to Kraus, an open structure call includes officers parking away from the house and approaching with caution, whereas a wellness check would have begun with a knock on the door. It’s not clear why the officers responded to an open structure call rather than a wellness check.

“To Mr. James Smith, I know you are hurting today as well. You called police to check on your neighbor because you cared about her safety and well-being,” Price said. “You were being a wonderful neighbor and doing the right thing to make sure she was OK. You are the type of person we all want living next door, watching out for us. Atatiana’s death has eroded your own your sense of safety and trust in law enforcement. I’m truly sorry.”

When Fort Worth police released body camera footage from the shooting, the department magnified a photo to highlight a gun laying in the room with Jefferson. Kraus said the gun was located just inside the window but declined to comment on whether Jefferson was holding it or not. On Monday, the mayor and police chief expressed regret for highlighting the detail. In her opening address, Price said the gun was “irrelevant” and that Jefferson was “a victim”.

“That is something we’ve done in the past to include the photograph of the firearm to show what the perceived threat may have been,” Kraus said. “In hindsight it was a bad thing to do.”

In a press conference prior to the announcement by Fort Worth police, Dallas-based civil rights attorney Lee Merritt, who is representing Jefferson’s family, called for the firing of Dean and an independent investigation of the shooting by federal authorities. After Dean’s resignation, Merritt demanded that the officer be prosecuted.

“The night that he murdered someone in their home, he should have been fired. He should not have been given the opportunity to resign, so we don’t consider that as anywhere close to a victory or an outcome that we’re considering,” Merritt said. “We are going to get Dean, that’s what we’ve come to expect, luckily, in the Dallas-Fort Worth area — that we go after bad cops. But we need to start systemically going after bad departments and poor leadership.”

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