Pushing aside charred sweaters, a cracked miniature Scotch bottle, a zipper, a photo of a baby girl, the slight, silver-haired man picked up some hunks of twisted metal. "This is from the corridor," he said, "and that's from the street outside."

In the cavernous hangar, police Lt. Kenneth W. O'Neil was tracking through the debris in pursuit of those responsible for the La Guardia Airport bombing that killed 11 and injured 51. "The object is to find the fragments of the device or container and ascertain how it was constructed and functioned," he explains in stiff official prose. "The big problem is figuring out which fragments belong to the blast, which are foreign to it."

Lieutenant O'Neil, 59, is head of the 17-man New York City bomb squad, the biggest and busiest in the nation. He is also a chemist who brings a rigorous scientific approach to his job. The crime and its aftermath are vastly emotional; not his investigation. "We deal in hard facts," he says. "We need physical evidence, real things like a piece of the bomb."

The force of the La Guardia blast—it was the equivalent of 15 to 25 sticks of dynamite—left few clues. Conspicuously absent, too, was the usual pre-explosion warning, which has led police to believe a deranged individual may have been responsible. "Groups usually like to get in on the act," O'Neil explains. "Whenever they say, 'Get everybody out of a certain area at such and such a time,' it's often true."

In recent years the bomb has replaced the bullet as a symbol of international insanity. In New York alone, more than half of the 32 bombings last year were blamed on terrorist groups. "It gets to be a sort of weird subculture," O'Neil shrugs. "Each little group goes around twisting facts their way. But for them it would make no sense to do the La Guardia bombing and then not stake a claim to it."

A mild-mannered man who says he rarely becomes depressed, O'Neil stops short of psychoanalyzing the culprits responsible for this or any other bombing—and he has investigated some 1,500 of them. "This one [La Guardia] is a field day for the psychiatrists," he says. "Some of them have come up with wild, surrealistic portraits." He is wryly amused by the attitude of some bombers: "They think they're great patriots. I had one fellow draw a diagram of his bomb and then sign it. He acted like Thomas Jefferson with the Declaration of Independence."

O'Neil's bomb squad handles about 5,000 cases a year, the majority of them false reports. He is greatly disturbed by the increasing number of deaths. "The bombs are bigger and more powerful, and the bombers are showing a greater disregard for human life." Part of the problem is the ready availability of bomb ingredients and instructions for building one. "You could make a nice bomb from the stuff in supermarkets and drug stores," says one bomb squad member. "Saltpeter, glycerine, lye. It's easier to make a bomb than to get a gun."

Created as a special unit of the New York City police department in 1905, the bomb squad was the first of its kind in the United States. Los Angeles, San Francisco, Chicago and Miami now are among the cities with similar full-time units. Bomb experts in some places have other police duties. "But New York City," says O'Neil, "has enough business to keep us going all the time."

His squad's job is to dispose of live bombs and determine whether explosions are accidental or intentional. "I admire the courage of the London bomb squad," O'Neil says. "They'll deactivate a bomb even at the risk of losing a squad member just to save the evidence. If someone says a bomb is going off in five minutes, London's force will run right in. Our approach is first to make sure everyone is out of a building. Then we may wait for the bomb to explode."

In O'Neil's career as squad C.O. he has faced anti-Castro terrorists who fired a bazooka at the United Nations in the 1960s. "They were very proud. They all thought they were Simón Bolívar." In a more recent investigation, he discovered that four people killed in a bomb blast at historic Fraunces Tavern—Puerto Rican nationalists claimed responsibility—had died only because they changed tables. "A quirk of fate—their new table was against the door where the bomb was."

After an explosion like the one at La Guardia, bomb squad men fill steel drums with fragments and ship them for analysis to a lab next to O'Neil's office. Using such complex instruments as the emission spectrograph, ultraviolet spectrophotometer and gas chromatograph, police technicians can determine what the fragments consist of—and, most crucial, whether they are parts of the bombs.

O'Neil is clearly more comfortable with these devices than with the gun he shoves under the seat of his car. The son of a Bronx bus driver, he graduated from Fordham University in 1938 with a chemistry degree but could not find a job because of the lingering Depression: "Police work looked attractive. It was better than decorating store windows." He spent the next 17 years on the beat, in the crime lab and as a Police Academy instructor. In 1958 he took over the bomb squad.

Married and the father of two grown children—Kenneth, 27, works for an insurance firm; Carolyn, 31, is married and teaches school in Iowa—O'Neil earns about $28,000 a year. He and his wife, Kathryn, have lived for the past 35 years in a five-room house in a middle-class section of Queens, N.Y. O'Neil claims his wife does not worry about him, but he admits there are other views of the bomb squad. "A man will come in for an interview," he says. "I'll tell him to discuss the job with his wife. The next day I'll get a call saying he changed his mind."

The men are on call around the clock, and O'Neil's own schedule leaves little time to indulge his passion for reading ("I can no longer read four mysteries at a time and keep the butlers straight") and theater ("I can't commit myself in advance"). His other hobbies are swimming and fishing and snowmobiling in winter at his country home in New Hampshire: "I get away from New York's problems there. I only hear about Boston."

While earning three citations for bravery, O'Neil was also piling up credits for an M.A. in chemistry and education at Hunter in 1963. Today he teaches forensic science at Rockland Community College and lectures around the U.S. and in Europe. "O'Neil teaches you about life," says one of his admirers, a 29-year-old bomb squad dog handler, Ronald McLean. "He never loses his cool in any situation."

Last week O'Neil stood for hours in the airport hangar, listening attentively as bomb squad members reported to him. He nodded and suggested new approaches. "Most of the time I don't think about danger," he says. "But every so often there is that moment when you're looking down at the little device at your feet and putting your hands on it and you know it could kill or maim you. But that's just a passing thing."

Lowering his azure eyes he surveys the debris around him and says: "I was standing at the airport after it opened again and saw people going about their personal concerns—getting their baggage, children running up to grandparents. These are strange times we live in. And this was a terrible thing."

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