The alleged murder of a white by a black struck a nerve in a city with a tortured history of race relations. Quiet, leafy West Roxbury is populated largely by Irish Catholics; it is a more prosperous version of South Boston, which precipitated the city’s grueling busing crisis. And the tale of a black leaping out of nowhere to cut down a white brought back grim memories of Charles Stuart, who set off a frenzy when he claimed a black man in a jogging jacket had murdered his pregnant wife, Carol. Stuart later committed suicide after his brother implicated him as the actual killer. Following last week’s shooting, the city’s black leaders pleaded for calm. “This case could become very polarizing,” said the Rev. Eugene Rivers. “We don’t want open season on young black males.” Conscious of black anxieties, Boston Police Commissioner Paul Evans privately assured leaders that he was not contemplating the indiscriminate rounding up of black suspects that so exacerbated racial tensions in the Stuart case.

But the killing also chilled prosecutors, both in Boston and across the country. It looked like a retaliatory gang hit–the first-ever such attack on a prosecutor in Massachusetts and one of only a handful nationally. McLaughlin specialized in prosecuting inner-city gangs like Walk Hill and KOz, named after the kilos and ounces of the drug trade, and investigators immediately assumed that a “gangbanger” was responsible. (In fact, McLaughlin was set to try just such a case last week.) “When something like this happens,” said Robert Ullman, a former assistant U.S. attorney, “a line has been crossed.”

But there has been little hard evidence so far. Police are depending mostly on tips now that investigators have turned up only a hooded sweat shirt (not necessarily one worn by the killer, police say), a bandanna and an unidentified fingerprint on McLaughlin’s Toyota. Accounts from eyewitnesses, who were gazing into the shadows from at least 20 feet away, have proved hazy. Original estimates of the shooter’s age have been broadened from 14 or 15 to “teenaged,” and the supposed height of 5 feet 6 abandoned. Even though McLaughlin’s wallet was found–full of cash and credit cards-buttoned inside his pocket, investigators are wondering whether this was actually a botched robbery, rather than a gang-style execution. Boston’s gangs lack the sophistication of their counterparts in New York and L.A., and police sources doubt any of Me-Laughlin’s targets could execute such a hit. And what advantage would a gang gain? “Let’s be serious about this,” says one of McLaughlin’s colleagues. “It makes sense to kill a witness, sure. But why kill a prosecutor? There’s always somebody else to pick up the file.”

What’s more, despite an impressive 75 percent conviction rate, McLaughlin himself was not the sort of prosecutor to inspire a burning thirst for vengeance. Almost six feet tall, rail-thin, with a bushy mustache, he was known to nearly everyone as a mild-mannered, witty, dedicated professional. The son of former lieutenant governor Edward McLaughlin, McLaughlin studied religion at Dartmouth, then earned his law degree going to Suffolk University Law School at night. His case files were invariably in perfect order, and his desk was so clean, says Suffolk County District Attorney Ralph Martin, it was “hygienic.” Unmarried, McLaughlin lived alone on a quiet street, where he could often be seen watering his front lawn or trimming the hedges, the few diversions from his work. Scrupulously fair, he once dispatched a police cruiser to help an opposing defense attorney find an exculpatory witness-even though that ended up blowing his own case. Now the cruisers are out in force–to find McLaughlin’s killer.