Darrell Ross—Officer Walmart to his colleagues in the Tulsa Police Department—operates for up to 10 hours a day out of the security office of a Walmart Supercenter in the city's northeast corner. It's a small, windowless space with six flatscreen monitors mounted on a pale blue cinder-block wall, and on this hot summer day, the room is packed. Four Walmart employees watch the monitors, which toggle among the dozens of cameras covering the store and parking lot, while doing paperwork and snacking on Cheez Whiz and Club Crackers. In a corner of the room, an off-duty sheriff's officer, hired by Walmart, makes small talk with the employees.

As soon as Ross walks in the door, around 2 p.m., he's presented with an 18-year-old who tried to leave the store with a microwave oven. Ross focuses his gaze and talks in a low voice to the young man, who just graduated from high school and plans to go into the military. He also attempts to calm the boy's mother, who rushed to the store and is worried that her son won't be able to enlist if he gets a criminal record. "You need to start taking responsibility for your actions," Ross tells the teenager. "You're a man now." He tells the mother that because it was the boy's first offense, he won't be arrested—but if he messes up twice more, he'll be charged with a felony. Ross slips a pair of reading glasses out of his bulletproof vest and writes the young man a summons to appear in court.