Among the most chilling details to emerge in the Orlando massacre is that the killer paused during his three-hour rampage at the Pulse nightclub to search Facebook for news about it.
"Pulse Orlando" and "shooting," Omar Mateen typed into his smartphone, investigators found.
His real-time search is a striking data point in what has become a pattern in mass shootings: Killers deeply attuned to their media coverage and in some cases engineering it.
The 2007 Virginia Tech shooter interrupted his killing spree to mail a videotape to NBC to claim credit and explain his motives. The 2014 Isla Vista killer posted a manifesto on YouTube. Others have discussed their plans in online forums.
Media outlets have long taken the position that they simply report the news. But experts who study mass violence say they are also part of the story, because the intense coverage that such tragedies receive can inspire new shooters.
The perpetrators of these attacks are often disillusioned young men, and they inhabit the same publicity-obsessed culture as everybody else. Killing offers the prospect of becoming a household name.
"This seems like a way to achieve some recognition and respect they lack in their daily lives," said Dewey Cornell, a forensic clinical psychologist at the University of Virginia.
"We live in a world where people are really conscious of their social standing and audience," he said.
Around the world, mass shooters have left suicide notes and manifestos describing how they were inspired by the 1999 killings at Columbine High School in Littleton, Colo., one of the first school massacres in the age of 24-hour cable news coverage.
Sherry Towers, a researcher at Arizona State University, has conducted one of the few studies looking at connections between shootings.
She spent most of her career studying how social behavior spreads diseases such as influenza and Ebola. But in 2014, after noticing three shootings within about 10 days on various college campuses, she began wondering whether mass violence was also contagious.
So she built a statistical model to analyze databases of hundreds of shootings.
The study found that shootings that occurred in schools or ones in which at least four people died — the sorts of incidents that receive widespread media coverage — occurred in clusters. That suggested to researchers the kind of copycat effect that has been well documented for suicides.
After the shootings, the risk of more shootings rose significantly and remained elevated for an average of 13 days, according to the analysis published last year in the journal PLOS One. However, the research found no increased risk after shootings in which at least three people were hit but not necessarily killed, incidents that are so common they usually receive only local news coverage.
"When there was likely to be national or international media coverage, those were the ones where we found contagion," Towers said.
Still, she said the phenomenon has its limits, noting that mass shootings remain rare in Canada even though most people there live close to the U.S. border and are exposed to the same news coverage.
The difference, she suggested, could be that Canadians have more regulated access to firearms.
Much more research is needed to dissect the various factors that may be at work, she said.
With few formal studies on the role of the media, experts can only offer observations.
Jack Levin, a criminologist at Northeastern University in Boston who has tracked mass killings, said that beginning with Columbine there was a rash of school shootings that generated widespread media coverage.
The killings stopped abruptly after the terror attacks of Sept. 11, 2001, and did not resume for several months, he said. With the media focused on a story far bigger than any shooting, he said, "We robbed the copycat phenomenon of its inspiration."
He also pointed to a trend of escalating death tolls in individual mass shootings, blaming the pattern on publicity-seeking.
"All these killers want the publicity," he said. "They want to go down in infamy. Achieving the highest body count is one way to do that."
"The media have not only a right but a responsibility to report the news," Levin said. "The problem is the way the news gets reported. The emphasis is usually not on the victims but on the killer. … We make celebrities out of monsters."
After the 2012 shooting at a movie theater in Aurora, Colo., some relatives of victims urged the media not to mention the shooter's name. Colorado Gov. John Hickenlooper would only refer to James E. Holmes as Suspect A.
Some news figures have also complied with that wish.
In a segment in which CNN's Anderson Cooper read the names of the 49 people killed in Orlando, he said that out of respect for the dead the network would not air the name or photograph of their killer. Some officials have also refused to refer to Mateen by name at news conferences.
It is impossible to know if such gestures matter to potential killers — or if a blackout on naming shooters would slow the violence.
In any case, the rise of social media has given them — as it has everybody else — a platform to rapidly spread whatever messages they choose without the help of traditional media outlets.
Moments before he opened fire at the Pulse nightclub, Mateen went to his Facebook page and posted his political views and various threats and demands.
Times staff writer Molly Hennessy-Fiske contributed to this report.