"He had taped up an enlargement of Sci-Tron's final moments on the wall facing his desk, where he could see it all the time. He offered us chairs, booted up his computer, and pulled up the video of our interrogation of Connor Grant that morning. The three of us watched it together, looking for something we'd missed. Something we should have asked. We strained for something useful or revealing. Straining through the nothing Grant had given us for any kind of lead. Brady said, "One more time." He reversed the video, hit Play. We watched again. Then we kicked it around for a while, concluding that, based on our combined decades of cop experience and gut instinct, the science teacher was not a team player. He"