In 2002, two days after Halloween, a police officer stepped out of a house in the small town of Navasota, Texas. He shielded his eyes from the early morning sunlight, then ducked under the band of yellow tape that surrounded the house. The officer had been working all night and really needed a break. So he went down to the sidewalk and lit a cigarette. And as he smoked, his eyes fell on a muddy ditch that ran alongside the street. He saw something in the ditch that looked out of place. He walked closer and crouched down to examine the object. And when he saw what it was, his heart started racing. Because lying in the ditch was a mask. Under different circumstances, finding a mask two days after Halloween wouldn’t be that strange. But this wasn’t the kind of mask you’d buy at a costume shop... and the officer had found it 25 yards from the site of a murder.