A uniformed guard named Officer Hansen rolled his heavy chair aside so we could stand behind his dark wooden desk.

The air in the little room smelled of floor wax and warm computer monitors.

Detective Miller plugged the drive into a gray desktop tower and clicked on a folder labeled with Saturday’s date.

“This first file is from the hallway camera right outside the neonatal intensive care unit at ten thirty-seven p.m.,” Officer Hansen said, pointing a black plastic pen at the screen.

On the glowing monitor, a grainy black-and-white figure walked briskly toward the secure double glass doors.