And of course, arrest records, public inquests and legal documents contain the gunmen’s names.

“There’s a compelling public interest in naming the gunman and what his circumstances were and how he pulled off the shooting,” said Kelly McBride, a media ethicist at the Poynter Institute. “If you don’t name the gunman and try and understand how he got his guns, what his motivations are and what might have prevented this, I don’t think that we’ll be any better off.”

Would it even have an effect? Social scientists have found a nexus between suicides and news coverage, suggesting that reports detailing methods and motives may drive others to kill themselves in similar ways. But the links between news coverage and mass shootings are far more tenuous, Ms. McBride said.

Social scientists and criminologists say the forces driving these shootings are a kaleidoscope of anger, revenge, insecurity, immaturity, mental illness, a desire for notoriety and myriad other factors, including easy access to weapons. In Colorado, the passage of tighter gun control laws did not prevent Mr. Pierson from legally buying the shotgun and ammunition he used to carry out the attack, officials said.

Dave Cullen, the author of “Columbine,” a book about the 1999 attack near Littleton, Colo., said that mass shootings were often public performances by frustrated young men who had suffered failures or loss. They were “about being heard and felt,” in the worst way, he said. In a September essay for BuzzFeed, he suggested that news coverage use suspects’ names “sparingly” during the first two days after a shooting.