Behavioral traits of a school shooter are lack of empathy, narcissistic, fragile egos, are socially inept, have poor coping skills or they externalize blame.
More than 80 percent of the school shooters had some sort of grievance with the school. Around 60 percent wanted revenge. Some found it as a way to solve their problems. Nearly 30 percent had a history of suicide or depression.
Vacher said emotional "leakage" of information is long term. Kids just don't snap. The signs are usually evident long before. These students usually have conversations with or make remarks to other kids. Many have violent drawings. They express their anger through poetry or writing, and the largest tool is the Internet.
School shooters have posted violent images on their web pages. Other red flags are a fascination with weapons, anger problems or lack of health social ties.
"We need to get kids to talk to us," Vacher said. "Four out of five shooters told at least one other person."
To anonymously report possible violence at school, call (866) SPEAK-UP.