The Navy Yard mass slaying in D.C. on Sept. 16 has gun-control advocates, Newtown parents and Connecticut senators scurrying for new action. And it has pundits wondering what is wrong in American society that produces so many brutal rampages.

Gun rights defenders, meanwhile pointed to failings in a security system that would allow clearance to a man with three arrests and mental health issues. In the end, however, the story boils down, again, to “crazed gunman slaughters innocent people.”

The gun homicide rate overall is down 49 percent since its 1993 peak, according to a May 2013 Pew Research Center report.

But these mass killings seem to be increasing in frequency — six of them since the Sandy Hook slayings and at least 20 during the Obama presidency.

Is there something about the digital age — with individuals spending long periods of time on the Internet without family in the room — that stokes anger and alienation?

Aaron Alexis, the shooter in the Navy Yard, not only had been exhibiting symptoms of mental illness for a decade but was known to play violent video games all night, acquaintances have said.

The New York Times quoted an official saying acquaintances knew Alexis was paranoid and delusional. As a Navy reservist, he showed a “pattern of misbehavior” including insubordination and absences.

And yet, in Virginia, he was able to stroll into a gun store and walk out with 12-gauge shotgun and ammunition, which he unloaded into strangers eating breakfast and officers trying to stop him, killing 12.

If this aftermath feels like deja vu, it is.

These shootings are as frustrating as they are perplexing and senseless. After an arrest for shooting out someone’s tires years ago, Alexis said he had some sort of anger-fueled blackout.

But anger issues lead to domestic incidents. What leads someone to smuggle in a shotgun to a place and deliberately kill as many strangers as you can, with little or no hope of escape? It begs the question of whether the notoriety of great evil has somehow become desirable.

Media moguls, like gun advocates, disavow any blame, even though some of the most violent TV shows right now are the most popular. Showtime’s “Dexter,” AMC’s “Breaking Bad” and FX’s “Sons of Anarchy” not only match the gore of “The Walking Dead” and “Criminal Minds” but they’re all about villains as antiheroes. The shows glorify sociopaths (although Dexter is a vigilante, if that’s any better).

In the same issue that reported on Alexis, the Times reviewed the latest version of the video game franchise “Grand Theft Auto.” The reviews starts out by saying, “the controversies that once surrounded the Grand Theft Auto games have begun to seem like sepia-toned oddities from another age.”

Maybe, to a sophisticated adult. But easy and alluring mass violence tells us something about technology’s dark side — that high-definition pictures encourage “action.” Pictures over words, video over print, danger over comfort.

The indisputable fact is that no-real life rampage — not Virginia Tech, Aurora or Sandy Hook — would be as lethal without a gun.

Connecticut took some action on gun control, but the U.S. Senate rejected expanded background checks for purchasers, despite public support. Let’s get that done first.

— The New Haven (Conn.) Register