Their numbers were predicted as ready to explode cataclysmically. Social scientists like James A. Fox, a criminologist, warned of “a blood bath of violence” that could soon wash over the land. That fear, verging on panic, is the subject of this week’s segment of Retro Report, a series of video documentaries that examine major news stories from years ago and explore what has happened since.

What happened with the superpredator jeremiads is that they proved to be nonsense. They were based on a notion that there would be hordes upon hordes of depraved teenagers resorting to unspeakable brutality, not tethered by conscience. No one in the mid-1990s promoted this theory with greater zeal, or with broader acceptance, than John J. DiIulio Jr., then a political scientist at Princeton. Chaos was upon us, Mr. DiIulio proclaimed back then in scholarly articles and television interviews. The demographics, he said, were inexorable. Politicians from both major parties, though more so on the right, picked up the cry. Many news organizations pounced on these sensational predictions and ran with them like a punt returner finding daylight.

But a funny thing happened on the way to the apocalypse. Instead of exploding, violence by children sharply declined. Murders committed by those ages 10 to 17 fell by roughly two-thirds from 1994 to 2011, according to statistics kept by the Justice Department’s Office of Juvenile Justice and Delinquency Prevention. Mugged by reality, a chastened Mr. DiIulio has offered a mea culpa. “Demography,” he says, “is not fate.” The trouble with his superpredator forecast, he told Retro Report, is that “once it was out there, there was no reeling it in.”

It certainly had consequences. It energized a movement, as one state after another enacted laws making it possible to try children as young as 13 or 14 as adults. (New York had such a law even earlier, and it is now being applied to Kahton Anderson.) Many hundreds of juveniles were sent to prison for life, though in the last few years the United States Supreme Court has ruled that such sentences must not be automatic, even in murder cases. Individual circumstances and possible mitigating factors should be weighed, the justices said.

Inescapably, superpredator dread had a racial component. What the doomsayers focused on, in the main, were young male African-Americans. For Steven A. Drizin, a law professor at Northwestern University writing for The Huffington Post last September, the deep-seated fear that any black teenager in a hoodie must be up to no good was essentially what got Trayvon Martin killed in Florida two years ago.