Compelling chronicle of California youth gangs, by Los Angeles Times staffer Sipchen. In 1990, over 600 people were killed in gang-related homicides in L.A. County alone. Here, Sipchen expertly reveals the gang world through the day-to-day life of Kevin Glass (``Baby Insane'') and the work of detective Patrick Birse (``the Buddha''), who persuaded Glass to turn informer. Glass grew up in a San Diego ghetto known as the `` `Hood,'' turf ruled by the all-black gang of the Neighborhood Crips. By age 11, Glass was smoking pot daily with his `` 'cuz's'' and for kicks stealing cars to lead the cops on high-speed chases. At 14, he was sentenced to three years in youth prison for 23 counts of armed robbery. Back in the 'Hood at 17, Glass and the Neighborhood Crips improved their technique. Stoned on PCP, they stole high- speed cars, carried police scanners, and--armed with automatic pistols, assault rifles, and hunting knives--descended on affluent areas of San Diego, robbing at random, sometimes ramming through storefronts for loads of fancy running suits. Glass, by now a crack addict, was nabbed by his parole officer and jailed pending a hearing when Birse sought him out. Besides his Buddha- like belly and mellow disposition, Birse had a singular talent for creating and working informers. With a promise that Glass wouldn't be reimprisoned, he got the young hoodlum to testify against the Neighborhood Crips. Throughout, Sipchen follows in depth the life and fate of every 'cuz in the 'Hood, as well as that of the Buddha, who worked only the most dangerous cases; and he offers such colorful details as the police name for drive-by shootings: ``AVANHI''--``Asshole vs. Asshole, No Human Involved.'' Superbly written and fresh: Along with LÇon Bing's Do or Die (1991), the clearest view to date of the exploding street-gang phenomena.