How to detect threatening behavior

Crime scene tape surrounds the Century 16 movie theater where 12 people were killed in a shooting rampage last Friday, on July 23, 2012 in Aurora, Colorado. Suspect James Holmes, 24, allegedly went on a shooting spree and killed 12 people and injured 58 during an early morning screening of 'The Dark Knight Rises.' (Photo by Kevork Djansezian/Getty Images)

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    How to detect threatening behavior

Experts discuss how to look for warning signs, in wake of the Aurora, Colorado, shooting.