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A sheriff investigating the deadly shooting in Roseburg, Oregon has said he will not speak the name of the gunman. But when it comes to copycat crimes, naming killers may be less important than the extent of the news coverage.

The name of the man who opened fire on an Oregon community college campus on Thursday, killing nine, was already widely known by the time Douglas County Sheriff John Hanlin came to speak to the media.

But Hanlin said he and his office would not be uttering the name of the deceased shooter, Chris Harper Mercer.

"I don't want to glorify the shooter, I don't want to glorify his name, I don't want to glorify his cause," Hanlin said. "You won't hear his name from me or this investigation."

On Friday, the sheriff stood fast on his promise, saying it would "only serve to encourage future shooters".

Image copyright Getty Images Image caption Sheriff John Hanlin said he would not name the gunman in the Roseburg, Oregon, mass shooting

In April, at the start of the Aurora theatre shooting trial, families of those killed in recent mass shootings sent a letter to 150 media organisations, asking them not to name shooter James Holmes, instead focusing their coverage on the massacre victims.

It's true that rampage shooters show a pattern of being "obsessed with the previous murders and obsessed with the tally," sociology professor Zeynep Tufekci told BBC World Have Your Say on Friday.

According to CNN, the gunman in the Oregon campus shooting had previously referenced Vester Flanagan in a blog post. Flanagan was the Virginia man who shot and killed two of his former colleagues on a live news broadcast and posted another video version of the crime on Twitter.

Mercer wrote that men like Flanagan are "alone and unknown... yet when they spill a little blood, the whole world knows who they are".

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"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 the more people you kill, the more you're in the limelight."

Research shows that, in fact, mass shooters may be more likely to act when there has recently been a high-profile mass killing, a model more attune to viral infection than pure copycat.

In 2014, Sherry Towers, a researcher at Arizona State University, had a meeting cancelled with some collaborators at Purdue University. Their school was on lockdown after a student walked into a class and shot dead a fellow classmate.

Towers heard about three other school shootings that same week and wondered if her work with models of contagion - "how people are infected with ideas" - would apply.

She studied three separate data sets - mass killings, in which more than four people were killed, mass shootings where less than four people were killed but at least three people were wounded, and school shootings, regardless of number of deceased or wounded.

Barack Obama and gun crime 15 statements by President Obama following mass shootings during his presidency 994 mass shootings since he was re-elected in 2012 Reuters

She found that school shootings and mass killings were more likely to have national news coverage, which correlated with a significant contagion effect.

After either kind of event, the probability of a similar event happening increased for the next 13 days.

But for mass shootings - where few people were killed but many might be wounded - coverage was largely limited to local outlets. There was no evidence of contagion.

Media playback is unsupported on your device Media caption How common are school shootings in the US?

Reid Meloy, a professor of psychiatry at University of California at San Diego, says mass shooters are usually part of two groups - vulnerable adolescents and older males who are "alienated and angry".

Young adults often identify with other people very intensely. If the "rest of their adolescent life is not going well" they may identify mass shooters as "a way to capture a sense of control and potency in their own lives".

Older male mass murders tend to have more established psychological issues or mental disorders - about 25% of mass murders are psychotic when they kill, Meloy says. But more often, he says, there is a "sense of being humiliated by life - the sense of being separated from other people".

"It tends to feed this notion of infamy seeking - and a desire to make one's mark in history," he says.

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Proponents for less media coverage of mass shootings say news organisations have a responsibility not to encourage future killings by limiting reporting on shooters, the same way most news organisations do not report on suicides for fear of creating a contagion effect.

"It's not a call for censorship," Tufekci said. "It's a call for a desensationalisation of the coverage and not giving the killer publicity on the terms he seeks."

But how do journalists put these ideas into practice while still reporting the news?

"We need to get the name of the killer out there - for information and because people who knew him may come out of the woodwork." says Dave Cullen, who wrote a book on the Columbine murders.

Still, he notes, "the usefulness of that pretty much stops" after the initial report.

He suggests using the name in print once per story or once per show for only the first day or two.

Image copyright Getty Images Image caption Family members of the 12 victims in the Colorado movie theatre shooting attend a vigil in 2012

"It's a public service and it's a thoughtful way of doing it," he said. "You should always break a rule when it makes sense."

A "much more profound" effect than limited naming of killers is the tenor and level of coverage, Cullen says, especially when facts are limited in a breaking news situation.

It may be a decision that US media increasingly makes, albeit unevenly. Anderson Cooper, of CNN and Megyn Kelly, of Fox News, have said publicly they will limit focus on mass killers in their own programmes.

But despite their high profile, the rest of their organisations have not followed.

On BBC World Have your Say on Friday, a news editor for WTOP, a local Washington broadcaster, said his website would publish the name and photo of the Oregon gunman, but not in a prominent position on the website.

Listen to more of this debate on the World Have Your Say podcast page