CONFESSIONS OF SON OF SAM by David Abrahamsen MD (Columbia University: $19.95). David Berkowitz, the "Son of Sam," killed six young people and crippled two others during the yearlong shooting spree that ended with his capture in August, 1977. The baby-faced Berkowitz terrorized New Yorkers with his .44 caliber revolver by attacking couples in parked cars. When Berkowitz decided to tell his story, he chose forensic psychiatrist David Abrahamsen, who helped write the New York State insanity law, and has authored 13 books. Abrahamsen received more than 155 letters from the killer, and had more than 50 hours of interviews with Berkowitz, his family, and others who knew him. What emerges is a jumble that suffers from leaden prose and pat psychological analysis. Describing his first meeting with Berkowitz, Abrahamsen writes, "As I sat in that cramped room at a small desk, worn from years of use, I had a foreboding of spending many long hours in this cubicle. The air was heavy . . . Suddenly I felt a presence." The "presence" was the sadistic, narcissistic, self-hating, parent-hating, Oedipus complex-tormented, castration-anxious Berkowitz. A book like this must have startling new perceptions, or a compelling narrative structure. Unfortunately, "Confessions of Son of Sam" offers neither.