INSIDE ROOM 309,a third-floor classroom in concrete-and-brick Van Allen Hall on the University of Iowa campus, Ken Nishikawa was standing at an old-fashioned blackboard. He was lecturing to a weekly graduate seminar in plasma physics when Dr. Lu Gang's first shot rang out. * At first, some of the graduate students in the room thought it might be a firecracker. It was Friday afternoon, last Nov. 1, and one of the students later recalled thinking it must be some sort of prank. "What are you doing, Lu Gang?" he thought to himself. "Halloween is over." The pretty blue smoke coming out of Lu Gang's .38-caliber revolver added to the unreality, the seeming playfulness of it all. * But it was no joke. In an instant, Prof. Christoph K. Goertz--one of America's top space physicists, a specialist on Jupiter and Saturn--slumped in his chair, bleeding from the back of his head. Lu Gang, who had been behind Goertz near the door, took a step to his left and fired again, directly into the face of Dr. Shan Linhua, Lu's former roommate, friend and rival within the Iowa physics and astronomy department. Shan fell. * By now, the other eight scientists in the room were diving under chairs or the brown, oval seminar table. Among them was Prof. Robert A. Smith, Goertz's protege, himself an expert on space and plasma physics. As Smith sought protection under the table, Lu took a step toward him and fired three shots, hitting Smith in the chest. Then Lu Gang walked out of the seminar room, turned right and down one flight of stairs. Between floors, Lu reloaded his Brazilian-made Taurus revolver. By the time he entered the bright, airy office of Prof. Dwight R. Nicholson, chairman of the department, he was ready to fire again. * Upstairs, panicked students scattered from the seminar into nearby classrooms, their hands trembling as they tried to lock the doors behind them. A Chinese student named Wu Li* stumbled into the room next to 309, dialed 911 for the police and handed the phone to an American, afraid that in the frenzy of the moment his usually trusty and long-studied English might jam in his throat. * Lu aimed three shots at Nicholson, wheeled and returned upstairs to the seminar room, where Smith was still alive. He fired again, finishing off Smith and, just to make sure, pumped one more round each into Goertz and Shan. * Lu's mission wasn't quite finished. He walked downstairs, exited the physics building and turned left. On a freezing-cold afternoon, he strode a full three blocks along the southern edge of the campus to Jessup Hall, the drab gray-stone administration building, where he asked for T. Anne Cleary, the university's associate vice president for academic affairs. Told she was unavailable, Lu grew angry, shouting and creating a stir until she appeared outside her office. He fired at Cleary, the bullet entering through her left nostril, then pivoted and fired again, striking Miya Rodolfo-Sioson, the 23-year-old Filipino-American student working as a temp outside Cleary's office, in the mouth.