Much of what is so disturbing about LaDue’s exchanges with Schroeder, in fact, is simply his version of the quintessential A.S.D. symptom of “restricted range of interests.” He’s obsessive. He insists on applying logic and analysis to things that most of us know we aren’t supposed to be logical and analytical about. What should he wear? The standard uniform for school shooters is a duster. But it didn’t make sense to wear a duster to school, LaDue explained, “because that’s a bit suspicious.” He’d store it in his locker. Where should the bombs go? Harris and Klebold had chosen the cafeteria. But LaDue felt that was too obvious—and, logistically, placing them in the hallway by the water fountains made more sense. When should he attack? April made the best sense, “because that’s the month that all the really bad tragedies happened like . . . Titanic, Columbine, Oklahoma City bombing, Boston bombing.” And what went wrong at Columbine, anyway? It was supposed to be a bomb attack. So why didn’t the devices planted by Harris and Klebold explode? “They were trying to create a circuit which would ignite some gasoline to hit the propane and cause a bleve—which is a boiling liquid expanding vapor explosion . . . which is basically the same thing as say a pipe bomb except with, like, gases,” LaDue patiently explained to Schroeder, before launching into a long technical digression on the relative merits of hydrazine, ammonium perchlorate, Cheddite, nitroglycerin, and flash powder. He was even more scathing about the Boston bombers’ use of pressure-cooker bombs. He thought they made a “crappy design of it.” They used nails and black powder from fireworks. It would have made far more sense to use flash powder and ball bearings, LaDue thought, because “spherical shrapnel” are “superior to nails in damage.” LaDue tells Schroeder that he has two YouTube channels devoted to his work. But anyone who watches the assembled videos expecting to see something macabre will be disappointed. They are home movies of LaDue testing whether tiny fuses will ignite when placed inside a plastic water bottle, or whether he can successfully blow a quarter-size hole in the side of a plastic playground slide. In the world before Columbine, people like LaDue played with chemistry sets in their basements and dreamed of being astronauts.