Experts who study mass shootings in the United States have found that would-be killers read up on those who came before them, signaling that "cultural contagion" is a factor behind their acts, The New York Times reports. Oregon community college shooter Christopher Harper Mercer, for example, had recently uploaded a video about the 2012 Sandy Hook Elementary School shooting in Newtown; the shooter at Sandy Hook had previously studied Columbine and the 2011 Norway attack in which 77 were killed.
"If you blast the names and faces of the shooters on news stations and constantly repeat their names, there may be an inadvertent process of creating a blueprint," Dr. Deborah Weisbrot, an associate clinical professor of psychiatry at Stony Brook University, told The New York Times.
In Germany, a study found that of nine school shootings, three of the attackers "consciously imitated and emulated what happened in Columbine." Another study found that mass killings tend to "cluster," or quickly follow one another — between 1997 and 2013, it appeared that the highest risk of an attack came within two weeks after a shooting was on the news.
Some regions in the U.S. are trying to intervene before killings can occur. In Los Angeles County, measures are in place for law enforcement, mental health departments, and educational institutions to recognize potentially dangerous behavior and act on it, stepping in when students are discovered with weapons or plans to carry out an attack. It's a fine line, however, navigating where the programs end and individual rights begin, especially when no crimes have yet been committed.
"The biggest problem we still deal with is underreaction to often blatant indicators that someone is moving on a pathway to violence," J. Kevin Cameron, an expert on mass shootings in the U.S., told the Times.