Recent events, like the shooting in San Bernardino, have investigators concerned about so-called "bedroom-" or self-radicalization.
The terrorist group ISIS is known for its success in recruiting members through social media without direct contact with those looking to pledge their allegiance.
A local retired specialist for the Department of Homeland Security says there are ways it can be prevented.
"What radicalization leads to, and one of the things you can watch for, is the increased withdrawal from society by a person," said Steve MacMartin, professor at Medaille College. "This increased intention and action of becoming alone and families, friends and loved ones should be able to see that. There should be enough of a change that they can question what's happening."
Authorities are still trying to determine how the suspects in the California shooting, Syed Rizwan Farook and Tashfeen Malik, were radicalized.
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