Likewise, other external factors, such as discontent with the government, or the disenfranchisement of a racial group, provide no simple template that ensconces all of this year's violent episodes. Indeed, a look at the eight mass murders so far this year reveal that some seem to have been sparked by domestic disputes, while others appear to have been triggered by social isolation, and others still seem completely random.
"This does not fit a single pattern, or even two or three patterns," Adler said.
But what does seem to be a common thread is anger. And Kopta said that uncovering the roots of this anger is critical to understanding these tragedies.
"Anger is the most seductive emotion of all," he said. "When people get angry, they don't want to stop being angry."
In his research, Kopta identified one potential source as media influence.
"We have not targeted any specific content," he said. "But some of it is very dark; it has to do with hatred of other people, or how unfair the world is."
It is a point with which Duwe disagrees. Rather, he said his research identifies 10 common threads that appear to link mass public shooting throughout U.S. history, including mental illness, social isolation, a motive of revenge and a triggering event that ultimately sets the horrific deed into motion.
Other patterns, such as a seeming increase during particular months, are most likely spurious, Kopta said.
"Is there something about March that makes people more at risk? I wouldn't think so," he said. "I would be careful creating patterns that aren't necessarily consistent with what is happening."
The unpredictable nature of mass murders makes preventing them a nearly insurmountable challenge, the researchers said. Still, some maintain that the United States can take steps to reduce the likelihood of such tragedies -- and few are more vocal than those with the Brady Campaign to Prevent Gun Violence.
"This particular month has just been a catastrophe for folks who do what we do; it's been a rough month," said Doug Pennington, spokesman for the Brady Campaign. "People aren't interested as much in what we have to say until something like this happens."
But he said the fact that all of these killings involved firearms offers a glaring clue as to what might be done to curb these episodes.
"From our perspective, we have encountered events like this for so long, and we interpret events like this less from the root causes and concentrate more on a common denominator," he said. "You don't have these events without a dangerous person getting their hands on a firearm. ... They're not using baseball bats, they're not using Frisbees, they're not using knives, they're not using any other weapons."
He said that the top three agenda items for the Brady Campaign are to enforce criminal background checks on all gun sales, to limit the bulk sales of handguns and to limit the availability of military-style assault weapons.