A lawyer for a white Oklahoma police officer accused of manslaughter 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 from her handgun.

Attorney Scott Wood says Tulsa officer Betty Shelby was experiencing "auditory exclusion," a condition in which people in high-stress situations often don't hear sounds around them.

Wood said Thursday that Shelby's defense won't hinge on whether she was aware of other officers on the scene, but it would be something important for jurors to know.

Shelby is expected to enter a not-guilty plea at her arraignment on Friday. She's charged with first-degree manslaughter in the Sept. 16 shooting death of 40-year-old Terence Crutcher.