The U.S. Secret Service has spent years studying assassins and school shooters to prevent mass shooting. Bryan Vossekuil and Robert Fein wrote two studies for the service told us about the warning signs in an interview for "60 Minutes."
Below is an excerpt of that interview.
Bryan Vossekuil: A strong key to prevention is to encourage those with information to come forward and to report it. And in almost every instance that we looked at there were such people. That, along the pathway that the attacker traveled -- people became aware of some of the behavior that included acquisition of a weapon or planning or surveillance. And they also became aware that the person was acting in a manner that would cause concern. That he was distressed about something.
Robert Fein: People who engaged in these attacks took a series of actions, as in often selecting a particular weapon, sometimes practicing with a weapon. They thought, "I'm desperate." They accepted the idea that violence might be an acceptable way to solve their problems.
Scott Pelley: How many school shootings did you study?
Pelley: How many cases did the shooter tell someone essentially what he was planning on doing before he did it?
Vossekuil: In almost all of them the student communicated his intent to commit the attack.
Pelley: The people who were told that something was going to happen, what did they do with the information?
Fein: Most often, they did not come forward and tell somebody.
Pelley: Why not?
Vossekuil: Some of them may have said that they thought that they might be getting the person in trouble by coming forward and that he really wasn't serious. In some [cases], perhaps they were afraid that if they brought this to the attention of an adult or a school official, that they would, in effect, ruin the life of the person that they were reporting.