Mental illness may be a common thread in several mass murders, but a police psychologist says that illness does not turn someone into a killer.
"What's happening is there's [sic] witch hunts against somebody who has a mental health issue," said Dr. John Nicoletti. "The majority of people who have a mental health issue are just trying to deal with it and are not violent."
Instead, Nicoletti says he looks for other signs of danger when he does a risk assessment of an individual. One is called a "perceived injustice" where the individual feels someone has done him wrong.
"The other things you can see by their writings and things is what's called the 'thrill of the thought'," he said.
That means the potential killer is excited by the idea of becoming famous through their acts.
"They're cowards and they believe if they do this -- and it is true -- that they will have notoriety forever," said Grant Whitus, a retired SWAT sergeant. "Their name will be remembered forever, even when they're dead. So we have to stop that from occurring."
Whitus was part of the team that responded to the Columbine High School shooting and he was the officer who found the killers in the library there.
"I do have the luxury of not having to worry about their psychological profile. I only concern myself with how to stop them and techniques on how to stop them, but there is certainly a pattern with the same type of person who is doing this," Whitus observed.
Nicoletti says that observant professionals and family members frequently spot the signs that lead to preventing these crimes, but those successful cases are never reported.
"The big thing is what we tell people, 'if somebody broadcasts it, you all need to believe it.' You need to take it seriously and you need to do something about it," he said.