JUST before Christmas, 1992, 18-year-old Wayne Lo strolled into a gun dealer in Pittsfield, Massachusetts and pointed to what he wanted - a US$150 SKS, a Chinese semi-automatic assault rifle. By state law, Lo would normally have had to wait 30 days during a background check. But under a loophole that speaks volumes about the anomalies of American gun law, the local student walked straight out of the shop with his purchase. He hailed from Montana, and as a non-local had managed to bypass the rules. The next morning, Lo was standing before a judge. With his new gun, he had returned to his college and shot to death a fellow student and a professor, and seriously wounded four other people. Emblazoned across his sweatshirt was the name of an underground rock band, perhaps the only clue to emerge so far as to why he did it. It read: Sick Of It All. Perhaps because of Lorena Bobbitt fever, or probably more likely because the country is becoming immune to the echo of gunfire, Lo's trial opened last week in Massachusetts to little national publicity. However, the small, taciturn defendant, with his military-style cropped hair, presents one of the most puzzling cases of random shooting, even in America's encyclopaedic history of the genre. Lo is thought to be the first ethnic Chinese immigrant to join the growing ranks of random shooting assailants. His closest criminal cousin may be Colin Ferguson, another immigrant (from Jamaica), who like Lo, seemed to harbour a paranoid resentment about racism in his new country, and who went on the recent bloody shooting spree on a Long Island commuter train, near New York. Both came from privileged backgrounds in their countries of origin, only to somehow get swept away in America's undercurrent of tension and violence - with easy access to the hardware to give vent to whatever hatred was eating them up. Lo was born in Tainan, Taiwan, to a military officer father and music teacher mother. The family spent a short time in Washington DC in 1981 when the father took a diplomatic posting, then returned to the US for good in 1987 when they settled in rural Montana to run a Chinese restaurant. Throughout his childhood, Lo had displayed a passion for the violin, and showed great promise. Academically, he was as hard-working as most Chinese immigrant children. His parents sent him to Simon's Rock College in Massachusetts in 1991, a liberal private high school renowned for alternative teaching methods to draw out the talent in its 300 students. It was in this new environment that Lo inexplicably went off the rails. He ditched his violin and Vivaldi for ''hardcore'' rock music, and hung out with a group of friends who kept to themselves and seemed to scorn their colleagues. ''They were and are elitist,'' recalled one student, Mishka Shubaly. ''He held himself above other people. A lot of it had to do with perfection.'' Although Lo complained about racism against him, he was said to hold equally disturbing views. One colleague said Lo once wrote an essay suggesting all AIDS victims should be banished to Utah, and others reported that he disliked blacks, Jews and gays. ON the morning of the killings, the college received for Lo a package in the mail containing ammunition. When his dormitory supervisors - with whom he had previously argued - grilled him about the contents, he said it was a present for his father back home in Montana. He was even asked to see the college dean, who later recalled Lo as coming across as ''calm, coherent, logical and open''. Coherent Lo may have been, but his lawyers are now claiming he was anything but logical. Later that day, he bought the SKS rifle, returned to school - bizarrely, to sit an end-of-term exam - and got ready for an act of horrific carnage. At around 10 that night, testified caretaker Teresa Beavers in court last week, she saw Lo with his gun approach the main campus gate near her hut. She was on the phone to her husband, who heard her put down the phone, and could only listen helplessly asshe shouted ''Oh my God, no!,'' and start screaming. Lo had shot her twice through the abdomen, injuries from which she was fortunate to recover. Mrs Beavers, 41, told the court that she was not scared at first, even though she saw a gun, because Lo ''looked very calm''. But then he fired. ''I threw myself on the floor and waited to die,'' she recalled. Luckily for her, he had seen another target, a 37-year-old language professor Nacunan Saez. He had no previous contact with the killer, but was merely driving his car past the scene. Lo shot him in the head, fatally. His then ventured to the library, where he killed an 18-year-old fellow pupil, and wounded another. Then to the dormitory, where he injured two more students. It was over in only a quarter of an hour. After Lo stopped firing, he put down his gun and called the police. Putting up his hands, he walked out into the street to be arrested. At the college graduation ceremony five months later, no less a figure than Senator Edward Kennedy attended, and tried to console the campus. ''What kind of country, what kind of society is this, where an emotionally disturbed teenager can walk into a sporting goods store, display an out-of-state driver's licence, plonk down US$150 in cash, walk out with his very own assault rifle, and open fire on his faculty and fellow students?'' the Senator asked. In court, prosecutor David Capeless has painted a picture of a heartless beast, who had bragged to fellow prisoners about his deeds. ''He talked about the number of people he shot, who he had shot and where he shot them,'' said Mr Capeless. ''You will hear how excited he was, how much he had wanted to do it, and how he regretted he hadn't shot more.'' He said Lo had said nine months before the killings that he intended to commit murder. The defendant, looking clean-cut in the dock, in blazer and grey trousers, has given no indication of any motive for his crime. But his lawyers will be pleading insanity to save him for a lifetime in jail. Meanwhile, his colleagues and family are trying to link the teenager who could play Vivaldi's Four Seasons from memory with great feeling, with the murderer who apparently had no feelings at all. ''Wayne is a fine boy, a lovely boy,'' said his mother, Lo Lin-lin. ''He cares about his family, he cares about friends. I really don't understand what happened.''