Questions surrounding the murder of 6-year-old JonBenet Ramsey in Boulder, Colo., 10 years ago returned this week, when embattled Dist. Atty. Mary Lacy of Boulder County ruled that, despite a confession, 41-year-old schoolteacher John Mark Karr would not be held on homicide charges.

DNA from crime scene samples did not match Karr’s. Nor did any evidence place him in Colorado, where he claimed he had been, at the time of the murder. Karr’s family said he had been in Georgia at the time of the beauty queen’s death.

Now this baffling case, in which JonBenet’s parents and brother were at one time or another considered suspects, is back where it began, a nightmare reawakened.

It might seem puzzling that so many people in this nation, which sees thousands of murders annually (2,000 children were murdered in 1996, the year of JonBenet’s death), would be so obsessed by one of them. (And maybe this is a question best put to the media, relentlessly obsessed for a decade.) But the Ramsey murder – in which a little girl was strangled, bludgeoned and possibly sexually abused in the basement of her home, without evidence of a break-in – cannot but have implications for parents throughout the country.

Because of stories like this one, each of us is on a heightened sense of alert when a child goes missing. We rarely can relax until we know, precisely, where our children are and that they are safe. It’s not so much this one murderer; it’s that there are even such people in the world.

Parents are haunted by this little girl’s death because it shocks us to realize a terrible truth: Unless we hold our children by the hand, every moment, we cannot protect them.

“Privileged middle-class paranoia asserting itself,” some may say. “A nation of overprotective parents projecting their hothouse fears on a world that’s not as lurid as their fantasies suggest.” Others will point out that the era of terror has overlapped with the Ramsey obsession. The world is a dangerous place, and we project our fears everywhere.

But I wonder if we should dismiss them so easily. Since there still is no conclusion to JonBenet’s story, we shudder at the possibilities that could strike our young. Now that the district attorney in Boulder has dropped charges, a killer remains on the loose somewhere in our country, and God only knows where. You can’t help wondering: Who was it? What neighborhood holds him or her? Such questions are precisely what so troubled the police in Atlanta during the Wayne Bertram Williams child murders of 1979 to 1981 – or any such murder.

For 10 years now, we have tried to dismiss JonBenet’s death as an aberration. But death is not an aberration – and neither, in this country, is violent death. When it comes to murder, we live in a terrible time. Nearly every evening’s news program reveals a new killing, if not in the wars in the Middle East, then the wars in our streets. Gangs. Drug factions. Stranger on stranger. A female hospital worker is shot to death while on her way to work in the early morning darkness. A youngster dies in the cross fire between warring factions in a neighborhood too close to our own. Hardly easy times.

We watched JonBenet prancing in a miniature beauty contest one day and read of her harrowing death the next. Doesn’t every parent internalize such catastrophes? A day without carnage in America is accidental. It is a rarity, or perhaps more to the point, the saddest of illusions.