Typically, shooters are individuals with a long history of frustration and failure, unable to cope with life's disappointments, according to Thornsley. He says that quite often the shooter blames others for their unhappiness.
According to Welner, there is a wide range of human behavior that manifests through a criminal act such as a shooting. He says the most predictable psychological quality in school shooters is blaming others for their shortcomings and feeling that others deserve punishment. There is also a component of paranoia, resentment, suspicion and contempt for those around them.
"The less specific a target is in a mass shooting, the more it involves generalized paranoia. You have to be contemptuous and dehumanizing to kill a stranger," Welner says.
The lack of emotional support with friends or family also adds to the shooter's frustration. "When a life problem has emerged and they are overwhelmed, or if they don't have a friend or therapist, that's a real problem," says Thornsley.The last resort
Some shooters experience what is referred to as a triggering or precipitating event prior to initiating a shooting, according to Thornsley, but it does not have to occur immediately before the crime.
Gasper concurs, and says there is a common misconception about shooters suddenly "snapping," when in reality the person has been planning a shooting for a long time.
"It's not something somebody decides to do overnight," Gasper explains. You can see that with the planning in the case of Cho. The thought had probably entered his mind, months beforehand, really as a last resort."Defining a shooter's intent
The Forensic Panel is a New York-based forensic science practice lead by Welner and is currently in the process of collecting data and researching the Depravity Scale. This project could change the way forensic science is included in criminal sentencing cases such as mass shootings.
According to The Forensic Panel, the Depravity Scale is a evidence-driven tool which will aid in establishing and standardizing a fair, consistent distinction of the worst crimes.
Legal terms for a crime such as "heinous," "atrocious," "evil" and "depraved" are currently used in the justice system to impact the severity of sentences — but with no consistent way of defining those terms.
The Forensic Panel indicates that the Depravity Scale will assess specific intents, actions, victimology and attitudes of a criminal about his actions. It focuses on the "what" of the crime rather than the "who" or the "why" to distinguish the aspects of a crime's fact pattern as a reflection of depravity and what warrants a more severe sentence.
Welner notes the Depravity Scale, which will be further developed into the Depravity Standard, will aspire to affect sentencing through societal representation. The Depravity Scale includes two ongoing surveys at www.depravityscale.org that urge the general public's participation — law enforcement as well as the communities it serves — to gather data on society's opinion of what elements of a crime are the worst of the worst. He hopes that through the data collection process the public will reach a consensus about the worst of crimes, regardless of background, and ultimately have public opinion influence the judicial system.
"The greatest significance about the Depravity Scale and the Depravity Standard research as it relates to law enforcement is that it focuses on the intent, the actions and the attitudes of a person about a particular crime," Welner says.
"No two murders, robberies or assaults are exactly the same," he continues. "Those of us who do case investigative work recognize there are features or qualities of a crime that do separate out the worst of crimes."
Welner says the Depravity Scale could have an influence on criminal sentencing and could change the way law enforcement professionals work. For instance, investigations would not be conducted solely for a verdict of guilt or innocence but would also uncover information about a motive and an individual's attitudes about the committed crime. As a result, evidence-based guidelines will give courts more information to consider about the type of crime, the intent of the criminal's actions and the criminal's attitude about his crime and whether any element does or does not distinguish that crime.