Mass shootings are defined as involving the indiscriminate killing of at least four people in public and they are all too common in the United States of America. Although the causes of these shootings are still unknown, researchers, analysts, behavioral specialists, and psychiatrists are actively searching for telltale signs in someone's behavior or attitude to aid in the prevention of such atrocities. However, as of now there are no cut-and-dry indications of a seemingly normal person slowly becoming a cold-blooded killer.

Individually, mass shooters have at least four commonalities amongst them: childhood violence or trauma, with mental instability as a result; problems in their careers resulting in high levels of stress or anxiety and usually accompanied by noticeable and seemingly abrupt changes in attitude or behavior; the tendency to copy previous shootings, which suggests ease of influence; and easy access to public shooting sites as well as guns, which usually belonged to a family member.

Even with these commonalities known and documented, it's still not enough to be able to predict mass public shootings. Most people that share these traits are not murderers, much less mass murderers.

"Even though the problem of mass shootings is enormous, the number of people who commit such acts is so small - a fraction of the population - that untangling a developmental pathway is likely beyond our reach at this time," says clinical psychologist Theodore Beauchaine of Ohio State University in Columbus.

In most cases, the shooters are young males who tend to post suggestive rhetoric on social media platforms usually days or even hours prior to carrying out the shootings. Therefore, scientists are now looking towards public policy rather than trying to pinpoint causes in individuals.

"Other lines of inquiry that do not focus on the individual may also be useful," says Philip Cook, a professor of economics and sociology at Duke University. Professor Cook has studied crime and its prevention for the last 50 years.

"Researchers need to focus on identifying ways to stop mass shootings before they happen," says Cook.

Public policy may be the first line of defense when it comes to public shootings. For instance, the study of how to best respond to "red-flag" behavior -- whether it be online or in person -- could prove beneficial to the refinement of laws designed to remove firearms from people who have been deemed dangerous and could potentially prevent other catastrophic mass shootings.

Studies also focusing on reasons as to why these shootings seem to occur in clusters could prove helpful. Similar studies were conducted focusing on media coverage of suicides and the ensuing rise of copycat suicides in the months following. Researchers now have statistical evidence of trending behaviors due to media coverage.