This spring, however, it became a cover. When something apparently snapped in Holmes’s head — turning a pleasant, pun-loving 24-year-old into a man allegedly planning a mass murder — his lonely life meant there were few people close enough to see any change.  On Sunday, new details emerged about the way Holmes allegedly began assembling ammunition and explosives, attracting little attention from acquaintances. Signals of his apparently troubled mind — an odd online personal ad, a bizarre phone message heard by a gun-shop owner — leaked out, but to strangers.  Many of those closest to him didn’t know anything had changed — not until everybody else knew, too.  “I was always trying to get into his head,” said one fellow neuroscience student, who spent dozens of hours in class with Holmes at the University of Colorado campus in Aurora. “If no one had ever said anything to him, he wouldn’t have said a word” all year.  Police say Holmes, wearing a gas mask and SWAT-style protective gear, killed 12 people in a shooting rampage at an Aurora theater early Friday. Another 58 people were injured in the attack.  On Monday, Holmes will have an initial court hearing. A man who had always seemed desperate to avoid any attention will have propelled himself into an international spotlight.  Holmes, who grew up in the suburbs of San Diego, is recalled by his high school classmates as friendly — but largely unmemorable.  “My good grades are partially thanks to him,” said Brian Martinez, 24, who was Holmes’s lab partner in chemistry. They collaborated in class, but didn’t see each other much afterward: Holmes was not at parties, and he didn’t seem to have a large circle of friends, Martinez said.  After graduating from the University of California-Riverside, Holmes came to Aurora last fall to study neuroscience — learning how electrical signals transmit sensations and ideas in the brain. His first-year class was small: The school takes an average of six new students a year. That group spends hours each day together in a small conference room.  One fellow student said that Holmes was often the first to arrive at class, riding from his nearby apartment on a BMX bike more fit for an adolescent. But once class began, he had a habit of daydreaming.  “It’s like you’re interrupting” another train of thought that Holmes was pondering, the student said. The student asked not to be named because the school had urged Holmes’s classmates not to talk to the news media.  Holmes volunteered little information about his own life outside of the classroom. His fellow students could remember just one personal detail that Holmes revealed without prompting: During a conversation about football, he said he was a San Diego Chargers fan.
James Holmes, the alleged gunman in the movie theater mass shooting early Friday, had a way of making himself invisible.