Nothing computes in the killing of Atatiana Jefferson, a 28-year-old pharmaceutical saleswoman who died after a police officer fired through a window into her house in Fort Worth, Texas, where she had been playing video games with her 8-year-old nephew early Saturday. Disturbing no one and breaking no laws, she was struck by a single bullet in her own bedroom and pronounced dead on the scene.

It does not compute that police, responding to a non-emergency call from a neighbor concerned only that Jefferson's front and side doors were ajar, parked out of view of the house. It makes no sense that the officer fired his weapon without identifying himself, having almost simultaneously shouted, "Show me your hands!" It makes no sense that in the hours after the shooting, Fort Worth police released a photo of a handgun in Jefferson's house — one she was legally entitled to possess — but without saying exactly where it was found or whether she had held it in her hand or pointed it at the officer.

Nothing computes about Jefferson's killing except for one thing: She was black, and the officer who killed her, Aaron Dean, was white. And that is an all-too familiar equation. He resigned Monday shortly before the police department planned to fire him, authorities said.

Innocent African American civilians are gunned down by white police so frequently that it would be willful blindness to deny a pattern. The circumstances vary, but the fact remains.

This time, the victim was a young woman hoping to attend medical school. Her ailing mother's house, where she was staying while she helped her mother recover from an injury, is in a working-class neighborhood populated mainly by blacks and Hispanics, in a city with a modest crime rate.

According to the police department, the officer, moving around the house's perimeter, saw Jefferson through her window and perceived "a threat." That is an assertion, not an explanation. The question in this case, as in so many other unwarranted police shootings, is what could make him feel under threat in such a situation.

It was just two weeks ago, in Dallas, that a white former police officer named Amber Guyger was convicted and sentenced to 10 years in prison for shooting her neighbor, an unarmed black man, Botham Jean, as he sat in his own apartment eating ice cream. She said she mistook his apartment for her own.

Jean's relatives, along with their lawyer and friends, said they hoped that trial's outcome, the exceedingly rare guilty verdict in an officer-involved killing, would send a message — that police are not entitled to shoot first and ask questions later; that officers must be trained to de-escalate; that the police departments' cultures and training regimens must be scrubbed for bias and accountability.

That message, if sent at all, does not seem to have been received a few miles away in Fort Worth. Again a family is calling for a transparent and impartial investigation — by an independent agency, not Fort Worth police, which have started a criminal investigation of the officer. They are entitled to that at the very least; so is every other American.

This editorial is the opinion of The Washington Post's editorial board.