A lawyer for a white Oklahoma police officer charged in an unarmed black man's death says she was so hyper-focused on the situation that she didn't hear other officers arrive on the scene or even the deadly gunshot she fired.

Tulsa officer Betty Shelby, who is expected to plead not guilty to first-degree manslaughter at her arraignment on Friday, experienced what is commonly called "auditory exclusion," a condition in which people in high-stress situations often don't hear sounds around them, her attorney Scott Wood says.

He says that while Shelby's defense won't hinge on whether she was aware of other officers when she shot 40-year-old Terence Crutcher on Sept. 16, it would be important for jurors to know.