There it was again. On the car radio after this morning’s school drop-off: The killer’s motives are unknown. Maybe you heard it on the evening news. Maybe it popped into your mobile device. Maybe it appeared in the morning paper.

The killer’s motives are unknown.

Which killer? I’m not naming names. This morning on the radio, it was a man in a van in Toronto. But it could have been the guy with no pants at the Waffle House, or the kid at the high school in Florida, or the sniper with the bump stock in Las Vegas ... the nightclub in Orlando, Florida ... the grade school in Sandy Hook, Connecticut ... the movie theatre in Aurora, Colorado ... the university in Virginia ...

His motives are unknown. So we must hear the killer’s name over and over again. We must view the same mug shot or driver’s licence photo with every update of the day’s headlines. (Maybe someone will find the motives in those blank, dull eyes.) The mass murderer’s unknown motives compel us to document his last weeks, last days, last hours, as if following his footsteps might lead us, like pirates with a treasure map, to a buried trunk full of why.

I suppose there is nothing new in this pursuit. The murderer’s mind is magnetic; drawing in Dostoevsky and Dreiser, captivating Capote, mesmerising Mailer. Last week, the Pulitzer Prize for feature writing was awarded to Rachel Kaadzi Ghansah for her powerful magazine essay in search of the motives behind the Charleston, South Carolina, church massacre.

Indeed, I’ve gone myself in search of motives. I have combed the psychiatric files of a serial killer and traced the movements of a firebomber. But that was a long time ago, and in the ensuing decades I’ve noticed a dismal sameness to these projects. The killer is alienated, aggrieved and grandiose. He is oversensitised to his own hurt and dead to the pain of others. Take a narcissist, stir in some paranoia, season with sociopathy, and there’s your deadly stew.

But it’s such an unsatisfying concoction. Our hunger for reason isn’t satisfied by a stew of irrational and non-rational factors. Mental distress is a what, not a why — or so it seems in the onward pursuit of the elusive motives.

Sometimes, the killer spells out his reasons, as the Charleston murderer did. He hated black people and hoped to start a race war. There was no deeper gloss than that, he insisted. “I don’t like it when people try to read into things, or try to find, or create meaning that isn’t there. I don’t like it when people put so much weight on the things I say,” the murderer wrote in his jailhouse journal.

Yet it’s never quite explanation enough, because no motive ever matches the awful weight and finality of the crime. We want something commensurate, something symmetrical, an injury or crusade equal to all the blood shed by innocent strangers. Instead we have only these small men with their lethal inadequacies.

If the only harm done were this communal disappointment — motives still unknown! reasons unexplained! — I would not be complaining. But evidence continues to accumulate that many of these killers are eager for their moment in this spotlight. “Directors will be fighting over this story,” said one of the Columbine High School gunmen in a pre-taped video testimony.

“Just look at how many fans you can find for all different types of mass murderers,” observed the Sandy Hook gunman.

“A man who was known by no one, is now known by everyone,” the gunman who attacked an Oregon community college observed. Writing admiringly of yet another homicidal enigma he had seen on television, the Oregon gunman continued: “His face splashed across every screen, his name across the lips of every person on the planet, all in the course of one day. Seems like the more people you kill, the more you’re in the limelight.”

And so it continues, new sickos stimulated by the images of the ones before, staking their own claims to a news cycle or two, their own faces flashed repeatedly on the screen, and their motives pronounced unknown. On the car radio this morning, there it was again: the reporter said the man in Toronto was a fan of the mass killer in Santa Barbara, California, who summed it up this way: “Infamy is better than total obscurity.”

So I ask my fellow journalists: when the killers themselves are telling us they draw inspiration from the prospect of our coverage, why do we continue to say their names and show their pictures? Nothing is ever learnt by doing this. No explanation requites the deadly facts. If nothing’s gained, what could be our motive — especially knowing that we might be supplying theirs?

David Von Drehle writes a twice-weekly column for The Washington Post. He was previously an editor-at-large for Time magazine, and is the author of four books, including Rise to Greatness: Abraham Lincoln and America’s Most Perilous Year and Triangle: The Fire That Changed America